Grenadier Tire Selection: AT vs MT, Load Ratings & Pressure
The INEOS Grenadier sits in a narrow category of vehicles where tire selection isn't cosmetic — it's structural. At approximately 5,950 pounds curb weight with a 7,716-pound GVWR, the Grenadier imposes demands on its tires that most SUV owners have never had to think about. The vehicle's solid axles, permanent four-wheel-drive system, and low-range transfer case mean that tire choice directly affects everything from highway stability to crawl-speed traction to how hard the TPMS screams at you on a 95°F afternoon.
This isn't a tire recommendation list. It's an engineering analysis — the math, physics, and field data behind why certain tires work on this vehicle and others don't. We'll cover the formulas you need to evaluate any tire, the tradeoffs between all-terrain and mud-terrain compounds, what load ratings actually mean when you're carrying 1,800 pounds of gear across the Simpson Desert, current retail pricing for popular options, and why the number on your door jamb sticker might be wrong for how you actually drive.
Every claim here is either derived from published specifications, calculated from first principles, or sourced from real owner reports. Where data is uncertain, we say so.
The OEM Baseline: What Ships on the Grenadier
INEOS offers two wheel/tire combinations from the factory. Both use a 6×130mm bolt pattern on 7.5"-wide rims:
Both configurations land at approximately 32 inches overall diameter, which isn't a coincidence — INEOS calibrated the speedometer, ABS, traction control, and gear ratios around this diameter. Change it, and you're changing the math the ECU is working with.
The 17" option is a Light Truck (LT) construction tire with Load Range E — meaning 10-ply rated sidewalls with a maximum inflation of 80 psi and a maximum load capacity of approximately 3,195 pounds per tire. The 18" option in the BFG KO2 variant carries a 117/114 load index, translating to 2,833 pounds per tire in single configuration at maximum pressure (65 psi).
These aren't arbitrary numbers. They matter.
Decoding the OEM Tire Sidewall
Let's break down what LT255/70R18 117/114S actually means, because most of these numbers become decision variables when you shop for replacements:
Sidewall Code: LT255/70R18 117/114S
The LT prefix matters most on the sidewall for Grenadier owners. LT tires are built to a different standard than P-metric (passenger) tires — thicker sidewall plies, higher maximum inflation pressures, and load ratings calculated per the Tire and Rim Association's engineering tables rather than the softer European ETRTO standards used for passenger tires. The Grenadier's weight and intended use demand LT construction. Running a P-metric tire on this vehicle — even in the same size — means operating outside the tire's designed load envelope.
Tire Diameter Math: The Formula Every Owner Needs
When comparing tire sizes, you need to convert metric tire designations into actual physical dimensions. The formula is straightforward:
D = overall diameter in inches
W = section width in mm (e.g., 255)
AR = aspect ratio as percentage (e.g., 70)
Rim = wheel diameter in inches (e.g., 18)
25.4 = mm-to-inch conversion factor
Applied to the OEM 255/70R18:
Sidewall height = 255 × 0.70 = 178.5 mm = 7.03"
Total diameter = (2 × 7.03) + 18 = 32.06"
Circumference = π × 32.06 = 100.7"
Revolutions per mile = 63,360 / 100.7 ≈ 629
BFGoodrich publishes 648 rev/mile for this tire — the difference comes from tread profile and tire deflection under load. Published figures are measured; calculated figures are geometric ideals.
This formula matters when evaluating upsized tires. Let's run the three most popular Grenadier upgrade sizes:
| Tire Size | Calculated ∅ | Width | ∅ Change vs OEM | Speedo Error |
|---|---|---|---|---|
| 255/70R18 (OEM) | 32.1" | 10.0" | — | — |
| 275/70R18 | 33.2" | 10.8" | +1.1" | -3.4% |
| 285/65R18 | 32.6" | 11.2" | +0.5" | -1.6% |
| 285/70R17 | 32.7" | 11.2" | +0.6" | -1.9% |
| 295/70R17 | 33.3" | 11.6" | +1.2" | -3.7% |
Speedometer Correction
Every increase in tire diameter makes your speedometer read lower than your actual speed. The formula:
Error = ((33.2 − 32.1) / 32.1) × 100 = −3.4%
At an indicated 70 mph, your actual speed is approximately 72.4 mph.
At an indicated 70 mph, your odometer accumulates roughly 2.4 fewer miles per 100.
Validation tip: After installing new tires, verify your actual speedometer error by comparing the indicated speed against a GPS speedometer app at a steady 60 mph on flat highway. GPS speed is independent of tire diameter and gives you the true correction factor for your specific tire.
A 3–4% error won't trigger check-engine lights or cause transmission hunting, but it compounds over time. After 30,000 indicated miles on a 3.4% oversized tire, your vehicle has actually traveled approximately 31,020 miles. Service intervals based on odometer readings will drift, resale mileage will be understated, and warranty claims tied to mileage thresholds get complicated.
All-Terrain vs. Mud-Terrain: An Engineering Comparison
The AT vs. MT decision is the most common tire question in Grenadier forums. It's also the most misunderstood, because the terminology suggests a simple terrain-based choice when the actual tradeoffs are far more nuanced.
What Actually Differs
All-terrain and mud-terrain tires aren't just different tread patterns stamped on the same carcass. They differ in at least five engineering dimensions:
All-Terrain (AT)
- Moderate void ratio (25–35%)
- Interlocking tread blocks with siping
- Optimized for pavement noise <72 dB
- Higher tread compound silica content
- 3PMSF snow rating available
- 40,000–60,000 mile tread life typical
- Better wet braking on pavement
Mud-Terrain (MT)
- High void ratio (35–50%+)
- Large, widely-spaced lugs
- Road noise typically 76–82+ dB
- Harder compound, fewer sipes
- Rarely 3PMSF rated
- 20,000–35,000 mile tread life typical
- Significantly longer wet braking distance
Void ratio is the percentage of the tire's contact patch that is open channel rather than rubber. It's the single variable that most defines the AT/MT spectrum. Higher void ratios shed mud and loose material more effectively — the wide channels between lugs allow material to self-clean as the tire rotates. But the same channels reduce the amount of rubber in contact with hard surfaces, decreasing grip on pavement, increasing braking distances, and generating more road noise as air pumps through the voids at speed.
"I owned a Jeep Wrangler JL Rubicon that came fitted with BFG Mud Terrains as stock and thought I was going to die young every time it rained. I swapped them for KO2's after 3,000 miles and the difference was night and day." — Grenadier forum member, TheINEOSForum
This isn't an exaggeration for dramatic effect. The physics are real. A high-void MT tire on wet pavement has dramatically less rubber contacting the road surface, and the reduced siping (those thin slits cut into tread blocks) means less ability to channel water out from under the contact patch. The result is measurably longer braking distances and reduced cornering grip in rain.
The Grenadier-Specific Calculus
The Grenadier's weight changes this equation compared to lighter vehicles. At approximately 6,000 pounds unloaded, each tire carries roughly 1,500 pounds — more when you factor in typical front weight bias from the inline-six engine. That load compresses the contact patch, which partially compensates for the MT's reduced void area on hard surfaces. But it also means the tire is working harder, generating more heat, and wearing faster.
For a vehicle that splits 70/30 between pavement and off-road (which describes most Grenadier owners), the AT category delivers a better engineering compromise. The tread life advantage alone — roughly 20,000 additional miles — translates to significant cost savings over 60,000 miles. For reference: a BFGoodrich KO2 in 265/70R17 (LT, Load Range E) retails for approximately $274 per tire (Tire Rack, accessed March 2026), while a comparable mud-terrain like the BFG KM3 in the same size runs approximately $310 per tire (Tire Rack, accessed March 2026). The AT's longer tread life means one fewer set of tires over 60,000 miles — a savings of approximately $1,100–$1,600 across a set of five (including spare).
MT tires make engineering sense in two scenarios: vehicles that regularly operate in deep, sticky clay or mud where self-cleaning is important, and vehicles used primarily for rock crawling at low speed where the aggressive sidewall lugs provide additional grip on irregular surfaces. For most Grenadier applications — fire roads, gravel, hard-packed desert, sand, even moderate rock — a well-engineered AT tire delivers equivalent or superior traction with dramatically better on-road behavior.
The KO2 Compound Variants
An important detail that most owners miss: the OEM BFG KO2 comes in two rubber compounds. The standard version uses a softer compound that earns the 3-Peak Mountain Snowflake (3PMSF) severe snow certification. The "DT" (Different Tread) variant uses a harder compound for longer wear but sacrifices the snow rating. Same tread pattern, different rubber.
"Not all KO2 tires are created equal. Not only are there load ratings of C, D, and E even within the same size tire, but in some sizes there is both a standard version (3PMSF) and a DT version. The user reviews of all of these tires are mixed together as if everyone is using the same tire." — Grenadier owner with 35+ years off-road experience, TheINEOSForum
This matters because negative reviews of the KO2 — particularly complaints about wet-road performance and premature wear — may be comparing fundamentally different products under the same name. When evaluating any AT tire, verify which compound variant you're purchasing. For Grenadier-relevant sizes: the BFG KO2 265/70R17 standard compound is BFG part number 08870, while the DT (longer-wearing) variant carries a different part number — confirm with your retailer, as BFG periodically updates part numbers by production year.
Load Ratings: The Math That Actually Matters
Load index is the most important safety number on a tire sidewall, and most owners ignore it. For a vehicle as heavy as the Grenadier, getting this wrong has real consequences.
Load Index Fundamentals
A load index number maps to a specific weight capacity in pounds at a specific inflation pressure. The relationship is standardized across the industry:
| Load Index | Max Load (lbs) | Max Load (kg) | Common Application |
|---|---|---|---|
| 110 | 2,337 | 1,060 | Light-duty AT |
| 113 | 2,535 | 1,150 | Standard LT |
| 115 | 2,679 | 1,215 | Heavy-duty LT |
| 117 (OEM) | 2,833 | 1,285 | Grenadier OEM spec |
| 120 | 3,086 | 1,400 | Heavy truck LT |
| 121 | 3,197 | 1,450 | Load Range E max |
Capacity vs. Actual Load
Here's the calculation that determines whether a tire is adequate for your Grenadier:
Approximate front/rear split at GVWR: 55/45
Heaviest single tire load (front, at GVWR): ~2,122 lbs
OEM tire capacity (LI 117): 2,833 lbs
Safety margin: 33.5%
This margin exists for a reason — dynamic loading during braking, cornering, and rough terrain can momentarily concentrate well over static weight on a single tire.
When owners consider downsizing to a standard load (SL) or P-metric tire for a softer ride, the math gets uncomfortable quickly:
"Also curious if I could get away with running Standard Load. They're 48 lbs vs the E-Rated at 64 lbs but the max load is 2,756 lbs at 44 psi vs 3,195 lbs at 80 psi. Given the weight of the vehicle is 6,000 lbs wouldn't the STD load at the lower PSI be acceptable?" — New Grenadier owner, TheINEOSForum
At curb weight with just a driver, the static load per tire is approximately 1,490 pounds. A standard-load tire at 2,756 pounds capacity provides a 1.85× safety factor — which sounds adequate until you consider that the Grenadier's rated payload capacity is 1,764 pounds. Add four passengers and gear, and the per-tire load climbs toward 1,930 pounds, reducing the safety factor to 1.43×. Add a roof rack with 200 pounds of gear and dynamic loading on rough roads, and you're approaching the engineering limit.
The short answer: maintain LT construction and a load index of 113 or higher. Below that, you're substituting your judgment for the vehicle engineers' calculations.
Load Range and Ply Rating
Load Range is frequently confused with ply count. Historically, a Load Range E tire was literally a 10-ply tire. Modern tires achieve equivalent strength ratings with fewer physical plies of stronger material, but the Load Range designation persists as a strength rating:
| Load Range | Equivalent Ply Rating | Max Pressure (psi) | Sidewall Stiffness | Weight Penalty |
|---|---|---|---|---|
| C | 6-ply | 50 | Moderate | Lightest |
| D | 8-ply | 65 | Firm | +3–5 lbs/tire |
| E (OEM) | 10-ply | 80 | Very stiff | +8–14 lbs/tire |
| F | 12-ply | 95 | Extremely stiff | +12–18 lbs/tire |
"In addition to having a heavier load rating than Load Range C, the E-rated tires have thicker, stronger sidewalls, which provide greater puncture resistance — and in rocky terrain this is great. I don't mind the stiffer ride, and I actually appreciate the firmness of the sidewall in the corners." — Off-road enthusiast, TheINEOSForum
Each step in Load Range adds rotational mass — unsprung weight that the suspension must control. Going from a Load Range C to Load Range E tire in the same size can add 30–50 pounds across all four corners. That's meaningful: unsprung weight directly affects ride quality, braking response, and acceleration. But the Grenadier was engineered around Load Range E. The spring rates, damper valving, and anti-roll bar calibration assume that sidewall stiffness. Dropping to a softer tire changes the dynamic behavior of the entire suspension system.
Tire Pressure Optimization: Why Your Grenadier Has Two Different Numbers
Tire pressure is heavily debated in Grenadier ownership. The vehicle has two published tire pressure specifications, and most dealers deliver vehicles set to the wrong one.
The door jamb placard is mandated by NHTSA in the US and shows the pressure required to safely carry the vehicle's maximum rated load (GVWR). The owner's manual provides load-adjusted recommendations. These aren't contradictory — they're different specifications for different conditions.
"Many dealers seem to be setting them to the door sticker pressure, which is for full GVWR. The manual states 36 PSI front and rear for up to 3 passengers — it greatly improves the road feel of the vehicle." — Grenadier owner, TheINEOSForum
Running 49 psi in the rear with no cargo is 36% over the recommended pressure for that load. The tire is overinflated, the contact patch is reduced to a narrow strip down the center, ride quality deteriorates, and center-strip wear accelerates. This is a common setup error on new Grenadiers, and it's the primary source of the "harsh ride" complaints that appear in early ownership reports.
The Physics of Pressure Selection
Tire pressure determines contact patch area through a direct physical relationship:
A = contact patch area (square inches)
W = weight on tire (pounds)
P = inflation pressure (psi)
Example: 1,500 lbs on a tire at 36 psi = 41.7 sq in contact patch
Same tire at 49 psi = 30.6 sq in — a 27% reduction in road contact.
"Contact Area = Vehicle Weight ÷ PSI. If you keep the PSI the same, a 30-inch and a 40-inch tire have the exact same square inches of contact on the road. The shape changes — taller tires give you a longer patch, wider tires give you a wider patch. The real trick: bigger tires have more air volume, allowing you to run lower pressure safely." — parb, TheINEOSForum (tire pressure engineering guide author)
This is the foundational insight that most tire discussions miss. Tire size doesn't directly increase contact area — pressure does. A larger tire allows you to run lower pressure safely (because the larger air volume means less proportional stress on the carcass), which then increases the contact patch. The tire is the enabler; the pressure is the mechanism.
Pressure by Terrain: A Working Reference
These ranges are compiled from owner reports, manufacturer data, and off-road engineering references. They assume stock LT tires (Load Range D or E) on a Grenadier at various loads:
| Terrain | Front (psi) | Rear (psi) | Notes |
|---|---|---|---|
| Highway (light load) | 36 | 36 | Per owner's manual, ≤3 passengers |
| Highway (loaded) | 40–43 | 45–49 | Scale pressure with actual load |
| Gravel/dirt road | 28–32 | 30–34 | Improved comfort, reduced vibration |
| Rocky trail | 18–24 | 20–26 | Sidewall flex absorbs impacts |
| Sand | 14–18 | 14–18 | Maximum flotation; monitor tire temp |
| Mud | 18–22 | 20–24 | Wider contact patch, beware bead unseating |
"I also use 28 psi on dirt roads. For technical 4WDing such as steep, rocky climbs I use 24 psi, and for soft beach sand I use 14 psi. As long as you're running tyres with strong sidewalls — LT construction — lowering tyre pressures makes you less vulnerable to punctures. Lower pressure allows the tyre to deform around objects better." — Grenadier owner with 10,000+ km, TheINEOSForum
Temperature Effects and TPMS Behavior
Tire pressure changes approximately 1 psi per 10°F of ambient temperature change. On the Grenadier, this creates a specific headache: the TPMS system has a narrow tolerance band and will trigger warnings for both over- and under-pressure conditions.
A tire set to 36 psi on a 50°F morning will read approximately 40 psi by afternoon on a 90°F day — purely from temperature, before any driving heat. Highway driving adds another 4–6 psi from friction-generated heat. The TPMS may trigger high-pressure warnings at pressures that were perfectly correct when cold.
"I find it really annoying that off-road mode doesn't mute the TPMS pressure alert. I'm pretty much always aired down when I'm in off-road mode." — Grenadier owner, TheINEOSForum
The workaround is to reset the TPMS reference point (via the off-road menu in the infotainment system) after airing down. The system will then alarm relative to your aired-down baseline rather than the factory-set reference. This isn't documented well in the owner's manual and is one of the most frequently asked questions in Grenadier communities.
Upsizing Tires: What Fits the Grenadier
The desire to run larger tires is nearly universal among Grenadier owners. Larger diameter increases ground clearance under the axles, and wider tread provides a larger contact patch when aired down. But the Grenadier has specific dimensional constraints that limit options — particularly around the spare tire carrier and the rear quarter-panel clearance at full suspension articulation.
Stock Fitment: Confirmed Sizes
The following sizes have been verified by owners on stock-height Grenadiers with no modification. "Confirmed" means installed, driven, and reported without rubbing at full lock and normal suspension travel:
| Size | Rim | Approx ∅ | Fitment Status | Spare Clearance |
|---|---|---|---|---|
| 255/70R18 (OEM) | 18" | 32.1" | OEM — no issues | Factory fit |
| 265/70R17 (OEM) | 17" | 31.6" | OEM — no issues | Factory fit |
| 275/70R18 | 18" | 33.2" | Confirmed — no rubbing | Tight but clears |
| 285/65R18 | 18" | 32.6" | Confirmed — no rubbing | Good clearance |
| 285/70R17 | 17" | 32.7" | Confirmed by multiple owners | Barely clears small door |
| 295/70R17 | 17" | 33.3" | Fits but tight — monitor at full lock | May require offset carrier |
| 285/70R18 | 18" | 33.6" | Reported rubbing by tire shops | Not recommended stock |
"No fitment or rubbing issues. That's why they recommended 285/65 instead of 285/70. Said 285/70 would rub." — Grenadier owner running 285/65R18 Nitto Recon Grapplers on stock 18" wheels, TheINEOSForum
The 275/70R18 has emerged as the consensus "sweet spot" for 18" wheel owners: a full inch of additional diameter for improved ground clearance, approximately 0.8" wider for better off-road flotation, with confirmed clearance on stock suspension. On 17" wheels, the 285/70R17 occupies the same niche.
"I run 34s and as wide as I can on the Grenadier — nearly maxed out without rubbing on a stock vehicle. The extra weight hurts highway MPG and acceleration, but the higher increase in footprint when aired down makes the trade-off worth it." — parb, TheINEOSForum
The Spare Tire Problem
The Grenadier's rear-mounted spare tire carrier has tighter dimensional constraints than the wheel wells. Multiple owners have reported that 33"+ tires on the spare carrier barely clear the small rear door, and some have switched to aftermarket carriers that offset or flip the spare position. If you upsize, verify that your chosen tire fits the carrier before you have five tires mounted and discover the fifth doesn't fit.
Load-Adjusted Pressure: Doing the Math Yourself
The factory pressure recommendations cover two conditions: light load and GVWR. Real-world driving falls everywhere in between. Here's how to calculate appropriate pressure for any actual load:
Prated = pressure at rated load from tire load tables
Wactual = actual weight on that tire (ideally measured via corner-weight scales)
Wrated = tire's rated load capacity at Prated
Example: Your tire is rated at 2,833 lbs at 65 psi (LI 117).
Actual corner weight: 1,600 lbs.
Ptarget = 65 × (1,600 / 2,833) = 36.7 psi
This confirms the owner's manual recommendation of 36 psi for light loads. The engineering checks out.
The ideal approach — which serious overlanders and expedition preparers actually use — is to weigh the vehicle loaded for your specific trip at a truck scale or with portable corner-weight scales, then calculate per-tire pressure from the tire manufacturer's load-inflation tables. These tables are available in the tire manufacturer's technical data sheets and show the load capacity at each pressure increment.
A low-tech validation method: draw a chalk line across the full width of the tread, drive 100 feet in a straight line on pavement, and inspect the wear pattern. If the center wears faster, pressure is too high. If the edges wear faster, pressure is too low. If the chalk wears evenly across the full width, the contact patch is correctly loaded for that pressure. Repeat after pressure adjustments. It's crude, but it works — and it accounts for the specific tire, load, and temperature conditions you're actually operating in.
The Weight Penalty: What Bigger Tires Actually Cost
Every tire discussion focuses on diameter and tread pattern. Few address the engineering cost that matters most for daily driving: rotational mass.
| Tire | Approx Weight | Δ vs OEM | 4-Tire Total Penalty |
|---|---|---|---|
| 255/70R18 KO2 (OEM) | 50.9 lbs | — | — |
| 275/70R18 AT (typical) | ~56 lbs | +5.1 lbs | +20 lbs |
| 285/70R17 KO2 LT/E | ~61 lbs | +10.1 lbs | +40 lbs |
| 295/70R17 KO2 LT/E | ~65 lbs | +14.1 lbs | +56 lbs |
| 315/70R17 MT (aggressive) | ~72 lbs | +21.1 lbs | +84 lbs |
Unsprung rotational mass has an outsized effect compared to static mass carried on the chassis. A commonly cited engineering approximation is that each pound of unsprung rotating weight has the equivalent dynamic effect of 4–7 pounds of static sprung weight. By that measure, an 84-pound tire upgrade has the dynamic equivalent of adding 330–590 pounds of cargo to the vehicle.
Practically, this translates to: slightly slower acceleration, slightly longer braking distances, 1–3 mpg reduction in fuel economy, and increased stress on wheel bearings, half-shafts, and brake components. For most owners, the tradeoff is worthwhile. But it's a tradeoff — not a free upgrade.
A Framework, Not a Recommendation
Rather than telling you which tire to buy, here's the decision framework that DVA Mechanics uses when customers ask:
The Five Questions
1. What's your actual usage split?
If more than 80% pavement: AT, LT construction, prioritize road manners and tread life. If more than 50% off-pavement in mud/clay: consider MT. If mixed terrain including sand, rock, and gravel: AT with aggressive siping outperforms MT in most conditions.
2. What's your typical loaded weight?
Daily driver with 1–2 occupants: 36 psi, and a load index of 113+ is sufficient margin. Expedition-loaded to GVWR regularly: maintain Load Range E and use the door sticker pressures. Calculate, don't guess.
3. Do you operate in snow?
If yes, require 3PMSF certification — not just the M+S designation (which has no standardized test). Verify the specific tire variant, as compound formulations within the same model name may differ in snow certification.
4. How much speedometer error can you tolerate?
Under 3% (up to ~33"): no practical impact on daily driving. Over 3%: consider a speedometer correction module, or accept the drift in odometer accuracy and service interval tracking.
5. Does the spare fit?
The most overlooked constraint. Verify before purchasing a fifth tire.
What Grenadier Owners Are Actually Running
Based on forum data across TheINEOSForum and r/ineosgrenadier, the most frequently reported tire configurations on Grenadiers are:
| Configuration | Size | Suspension | Popularity |
|---|---|---|---|
| Stock OEM | 255/70R18 or 265/70R17 | Stock | Most Common |
| Mild upsize (18") | 275/70R18 | Stock | Popular |
| Mild upsize (17") | 285/70R17 | Stock | Popular |
| Max stock fitment | 295/70R17 | Stock or 40mm lift | Enthusiast |
| 35" build | 315/70R17 or equivalent | 2"+ lift required | Rare |
The community trend is clear: most owners who change tires go one size up (∼33") on stock suspension and stop there. The vehicle's geometry, gearing, and overall height (already the tallest in its class at stock) don't reward aggressive upsizing the way a shorter vehicle might. The Grenadier isn't a Wrangler — it doesn't need 35s to perform.
"I think 35s would be cool, but you can't get anything bigger than 285/70R17 in a real snow tire, so I stuck with 33s, stock height. Big tires are great for real rock crawling, but so is a disposable body. If you want to run middle difficulty stuff and maybe daily drive it, the Grenadier seems fine." — Grenadier owner, r/ineosgrenadier
Tire Cost Comparison: 265/70R17 All-Terrain Options
Tire selection isn't just about performance specs — budget matters. Here's what the leading all-terrain options cost in the Grenadier's stock LT265/70R17 size as of March 2026. All prices reflect Load Range E (10-ply) variants where available, which is what most Grenadier owners run.
| Tire | Type | Price per Tire | Set of 5* | Source |
|---|---|---|---|---|
| BFGoodrich All-Terrain T/A KO2 | AT | $285–$290 | $1,425–$1,450 | Walmart / SpeedyTire, Mar 2026 |
| Falken Wildpeak A/T3W | AT | $230–$250 | $1,150–$1,250 | Walmart / Fitment Industries, Mar 2026 |
| Cooper Discoverer AT3 LT | AT | $224–$272 | $1,120–$1,360 | Walmart / SpeedyTire, Mar 2026 |
| Toyo Open Country A/T III | AT | $314–$343 | $1,570–$1,715 | Big O Tires / OK4WD, Mar 2026 |
| Mickey Thompson Baja Boss A/T | AT | $249–$260 | $1,245–$1,300 | JEGS, Mar 2026 |
*Set of 5 includes full-size spare. Prices from Walmart, SpeedyTire, Big O Tires, Fitment Industries, JEGS, and OK4WD as of March 2026; prices vary by retailer, region, and seasonal promotions. TireRack.com is another major retailer worth checking for competitive pricing. The Grenadier carries a full-size spare on the rear door (Wagon) or bed (Quartermaster). Prices are per tire, before mounting and balancing.
Living with the TPMS: Practical Notes
The Grenadier's TPMS system uses indirect measurement (wheel speed sensors) rather than direct pressure sensors in the valve stems. This means it detects pressure changes through variations in wheel rotational speed — a lower-pressure tire has a slightly smaller effective rolling radius and rotates faster.
The practical implications for tire selection:
Upsized tires: After changing tire sizes, the TPMS must be recalibrated via the off-road menu. Without recalibration, the system's baseline is wrong and will generate false alerts.
Airing down: Before airing down for off-road use, reset the TPMS reference point at your aired-down pressure. This prevents continuous low-pressure warnings while you're intentionally running reduced pressure on trails.
Temperature swings: Owners in desert and high-altitude environments report particularly aggressive TPMS behavior due to the narrow alert tolerance and large diurnal temperature swings. A 40°F overnight-to-afternoon swing produces approximately 4 psi of pressure change — enough to trigger alerts in both directions.
"I typically run 18–20 psi on rocks. I have a 7,500-pound Grenadier though. I could go down to 15. At 12, I would want beadlocks." — parb, TheINEOSForum
At pressures below approximately 12–15 psi, the risk of bead separation increases — meaning the tire can unseat from the rim during hard cornering or side-loading. Beadlock wheels physically clamp the tire bead to the rim, eliminating this risk. The Grenadier is available with factory beadlock-style wheels on certain trims, though true mechanical beadlocks (with bolted clamp rings) remain an aftermarket addition.
The Engineering Summary
Tire selection on the Grenadier comes down to a series of engineering tradeoffs, not brand loyalty. Here's what the data says:
Size
33" (275/70R18 or 285/70R17) is the practical maximum on stock suspension without compromising spare fitment or speedometer accuracy beyond 4%.
Construction
LT construction, Load Index 113+, Load Range D or E. The vehicle's weight demands it. P-metric tires are not appropriate regardless of listed load capacity.
Pressure
36 psi for daily driving. Scale to load. Air down by terrain. Use the owner's manual, not just the door sticker. Reset TPMS after every change.
The Grenadier's engineering team chose the BFG KO2 for a reason — it's a competent all-terrain tire with LT construction, strong sidewalls, and global availability. That last point matters more than most owners realize: if you need a replacement tire in rural Botswana, central Australia, or northern Scotland, a tire in a common global size on a standard 6×130 bolt pattern gives you the best chance of finding one.
Change tires if your specific use case demands it. But change them with the math, not just the marketing.