Data sheet TS-285/65R18 · Size
285/65R18 in inches
By the formula 285/65R18 measures 32.6 in (828 mm) overall diameter. It has a 11.2 in (285 mm) section width and 619 revs per mile (385 per km).
Fig. 1 — Cross-section
Table 1 — Nominal dimensions
| Item | in | mm |
|---|---|---|
| DOverall diameter | 32.59 | 828 |
| ASection width | 11.22 | 285 |
| BSidewall | 7.29 | 185.3 |
| CRim | 18 | 457.2 |
| Circumference | 102.4 | 2,600 |
| Revs per mile · km | 619 | 385 |
| Flotation size printed | 33X11.50R18LT | Mickey Thompson |
|---|---|---|
| Measuring rim | 8.5″ | Nitto LT |
| Approved rims | 8.5–10.0, 8.0–10.0″ | 15 LT tires |
Table 2 — Measured range
32.56–33.40″overall diameter, 17 tires from 5 makers (math: 32.59″)
50–67 lbweight, 15 LT versions
13.6–20.0/32″new tread depth
3,640 lbmax load per tire, 13 of 15 LT versions list it, as published
15 LT · 2 Pversions in the makers’ tables we read
All 17 tires ↓Table 3
17 tires in 285/65R18, as published
One row per model and type, from each maker’s size table. LT first, then P-metric; sorted by diameter.
The math says 32.59″. 17 tires from 5 makers measure 32.56″–33.40″. Tallest here: Mickey Thompson Baja Boss M/T (mud-terrain), 33.40″. Check the maker’s number before you buy for a tight fit.
| Tire | Type | Diameter | Width | Rims, in | Weight | Tread | Max load |
|---|---|---|---|---|---|---|---|
| Nitto Ridge Grapplernittotire.com · Oct 15, 2026 | LT · E 125/122Q | 32.56″ | 11.50″ | 8.5–10.0 | 58.3 lb | 16.4/32″ | 3,640 lb @ 80 psi |
| Nitto Recon Grappler A/Tnittotire.com · Oct 15, 2026 | LT · E 125/122R | 32.56″ | 11.50″ | 8.5–10.0 | 56.0 lb | 16.0/32″ | 3,640 lb @ 80 psi |
| Nitto Terra Grappler G3nittotire.com · Oct 15, 2026 | LT · E 125/122S | 32.56″ | 11.50″ | 8.5–10.0 | 54.0 lb | 16.0/32″ | 3,640 lb @ 80 psi |
| Firestone Destination X/Tfirestonetire.com · Oct 15, 2026 | LT · E 125R | 32.60″ | — | 8.0–10.0 | 50.3 lb | 16.0/32″ | — |
| Firestone Destination M/T2firestonetire.com · Oct 15, 2026 | LT · E 125Q | 32.60″ | — | 8.0–10.0 | 57.8 lb | 20.0/32″ | — |
| Kumho Road Venture AT52kumhotireusa.com · Oct 15, 2026 | LT · E 125/122S | 32.60″ | 11.50″ | 8.5–10.0 | 54.9 lb | 16.0/32″ | 3,640 lb @ 80 psi |
| Kumho Road Venture RTkumhotireusa.com · Oct 15, 2026 | LT · E 125/122R | 32.60″ | 11.50″ | 8.5–10.0 | 60.4 lb | 17.3/32″ | 3,640 lb @ 80 psi |
| Toyo Open Country A/T IIItoyotires.com · Oct 15, 2026 | LT · E 125/122S | 32.60″ | 11.50″ | 8.5–10.0 | 55.0 lb | 16.5/32″ | 3,640 lb @ 80 psi |
| Toyo Open Country R/T Trailtoyotires.com · Oct 15, 2026 | LT · E 125/122Q | 32.60″ | 11.50″ | 8.5–10.0 | 56.0 lb | 16.5/32″ | 3,640 lb @ 80 psi |
| Toyo Open Country R/Ttoyotires.com · Oct 15, 2026 | LT · E 125/122Q | 32.80″ | 11.50″ | 8.0–10.0 | 59.0 lb | 16.4/32″ | 3,640 lb @ 80 psi |
| Toyo Open Country M/Ttoyotires.com · Oct 15, 2026 | LT · E 125/122Q | 32.80″ | 11.50″ | 8.5–10.0 | 67.0 lb | 18.9/32″ | 3,640 lb @ 80 psi |
| Nitto Trail Grappler M/Tnittotire.com · Oct 15, 2026 | LT · E 125/122Q | 32.83″ | 11.93″ | 8.5–10.0 | 67.3 lb | 18.9/32″ | 3,640 lb @ 80 psi |
| Mickey Thompson Baja Legend EXPmickeythompsontires.com · Oct 15, 2026 | LT · E 125Q | 33.00″ | 11.50″ | 8.0–10.0 | 58.0 lb | 18.5/32″ | 3,640 lb @ 80 psi |
| Mickey Thompson Baja Boss A/Tmickeythompsontires.com · Oct 15, 2026 | LT · E 125Q | 33.20″ | 10.90″ | 8.0–10.0 | 64.0 lb | 18.5/32″ | 3,640 lb @ 80 psi |
| Mickey Thompson Baja Boss M/Tmickeythompsontires.com · Oct 15, 2026 | LT · E 125Q | 33.40″ | 11.20″ | 8.0–10.0 | 64.0 lb | 19.0/32″ | 3,640 lb @ 80 psi |
| Nitto Recon Grappler A/Tnittotire.com · Oct 15, 2026 | XL 116T | 32.56″ | 11.50″ | 8.0–10.0 | 47.0 lb | 13.6/32″ | 2,756 lb @ 50 psi |
| Nitto Terra Grappler G3nittotire.com · Oct 15, 2026 | SL 116T | 32.56″ | 11.50″ | 8.0–10.0 | 47.8 lb | 13.6/32″ | 2,756 lb @ 44 psi |
§ 1
Size by the formula
Overall diameter 32.6 in (828 mm) by the formula. Section width 11.2 in (285 mm). Sidewall height 7.3 in (185 mm). Rim 18 in (457 mm).
Circumference 102.4 in (2,600 mm) and 619 revolutions per mile (385 per km). These are unloaded nominal numbers calculated with the standard formula for tire sizes.
§ 2
What makers publish
Tire makers' size tables list 17 tires in 285/65R18 from 5 brands, with 15 LT and 2 P-metric versions. Listed load ranges include SL, XL and E. Published overall diameters run from 32.56 in to 33.4 in, against 32.59 in by the formula.
Weights in makers' tables run from 47 lbs to 67.3 lbs. New tread depths run from 13.6/32 in to 20/32 in. The size tables were checked October 15, 2026.
- Nitto Ridge Grappler LT285/65R18 — diameter 32.56 in, overall width inflated 11.5 in, weight 58.3 lbs, tread depth 16.4/32 in (Nitto, checked October 15, 2026).
- Toyo Open Country A/T III LT285/65R18 — diameter 32.6 in, overall width inflated 11.5 in, weight 55 lbs, maker lists 638 revs per mile (Toyo, checked October 15, 2026).
- Mickey Thompson Baja Legend EXP LT285/65R18 — diameter 33.0 in, section width 11.5 in, weight 58 lbs, maker lists equivalent 33X11.50R18LT (Mickey Thompson, checked October 15, 2026).
§ 3
Closest sizes and effects
The ±3% window is a tire-shop rule of thumb, not a law. Sizes within that window include 265/70R18, 305/65R17, 285/70R17, 305/60R18, 235/80R18 and various 33x11.50 and 33x12.50 listings.
Small changes in diameter change speedometer reading, revs per mile and axle clearance. Use the comparison tool or the speedometer calculator for precise swaps.
- 265/70R18 — diameter 32.6 in, +0.1%; indicated 60 mph → true 60.0 mph; revs per mile 619 → 619.
- 285/70R17 — diameter 32.7 in, +0.4%; indicated 60 mph → true 60.2 mph; axle clearance +0.06 in (+2 mm).
Fig. 2
285/65R18 and the sizes next to it
To scale, on one ground line. Diameter by the formula.
Table 4
Compare 285/65R18 with another size
Type any size: diameter, sidewall, speedometer and clearance change against this one.
Comparison
275/70R18 is 33.16″ tall, +1.75% against 285/65R18. At 60 mph on the dial you drive 61.1 mph.
| Item | 285/65R18 | 275/70R18 | Change |
|---|---|---|---|
| Overall diameter | 32.59″ | 33.16″ | +0.57″ +1.75% |
| Section width | 11.22″ | 10.83″ | −0.39″ |
| Sidewall | 7.29″ | 7.58″ | +0.29″ |
| Circumference | 102.4″ | 104.2″ | +1.8″ |
| Revs per mile | 619 | 608 | −11 |
| Axle height | 16.29″ | 16.58″ | +0.29″ |
When the odometer counts 1,000 miles, you have driven 1,017.5 miles.
Engine RPM at the same road speed: −1.7%. Gear ratio calculator
Speedometer
| Dial shows | True speed | Difference |
|---|---|---|
| 30 mph | 30.5 mph | +0.5 |
| 45 mph | 45.8 mph | +0.8 |
| 60 mph | 61.1 mph | +1.1 |
| 70 mph | 71.2 mph | +1.2 |
| 80 mph | 81.4 mph | +1.4 |
285/65R18275/70R18
Note 1
P-metric or LT in the same size
Nitto Recon Grappler A/T is published in both versions.
| Nitto Recon Grappler A/T | P · 116T | LT · E · 125/122R |
|---|---|---|
| Overall diameter | 32.56″ | 32.56″ |
| Max load | 2,756 lb @ 50 psi | 3,640 lb @ 80 psi |
| Weight | 47.0 lb | 56.0 lb |
| Tread depth | 13.6/32″ | 16.0/32″ |
| Approved rims | 8.0–10.0″ | 8.5–10.0″ |
Source: Nitto size table, checked Oct 15, 2026. On trucks and SUVs, the load ratings of the tires on an axle must add up to at least the axle’s GAWR on the certification label (49 CFR 571.110).
Vehicles on 285/65R18: not listed yet. We add a vehicle here only from its maker’s own spec sheet for that year and trim.
The size your vehicle left the factory on is printed on the tire and loading placard on the driver’s door jamb (49 CFR 571.110). Pressure and load: that placard too.
Table 5
Within 3% of 285/65R18
Same rim or ±1″, diameter within 3%. A shop rule of thumb, not a law.
| Size | Diameter | Width | vs 285/65R18 | At 60 mph | Clearance |
|---|---|---|---|---|---|
| 265/70R18 | 32.61″ | 10.4″ | +0.1% | 60.0 | +0.01″ |
| 305/65R17 | 32.61″ | 12.0″ | +0.1% | 60.0 | +0.01″ |
| 285/70R17 | 32.71″ | 11.2″ | +0.4% | 60.2 | +0.06″ |
| 305/60R18 | 32.41″ | 12.0″ | −0.5% | 59.7 | −0.09″ |
| 235/80R18 | 32.80″ | 9.3″ | +0.7% | 60.4 | +0.11″ |
| 33x11.50R17 | 33.00″ | 11.5″ | +1.3% | 60.8 | +0.21″ |
| 33x11.50R18 | 33.00″ | 11.5″ | +1.3% | 60.8 | +0.21″ |
| 33x12.50R17 | 33.00″ | 12.5″ | +1.3% | 60.8 | +0.21″ |
| 33x12.50R18 | 33.00″ | 12.5″ | +1.3% | 60.8 | +0.21″ |
| 275/70R17 | 32.16″ | 10.8″ | −1.3% | 59.2 | −0.21″ |
Q&A
Common questions
How big is 285/65R18 in inches?
By the formula overall diameter is 32.6 in (828 mm) and section width is 11.2 in (285 mm). Revolutions per mile are 619 (385 per km).
Do makers publish different diameters?
Yes. Makers' published overall diameters run from 32.56 in to 33.4 in versus the nominal 32.59–32.6 in by the formula, depending on model and construction.
Will the speedometer change?
Small diameter changes produce small speedometer differences. For example, moving to 285/70R17 changes indicated 60 mph to about 60.2 mph; moving to 265/70R18 leaves 60.0 mph unchanged.
Where is tire inflation and load information?
See the tire and loading placard on the driver's door jamb for the vehicle maker's recommended cold inflation pressures. The tire sidewall shows the maximum load rating and, for LT tires, the load range letter (49 CFR 571.110; 49 CFR 571.139).
Notes
Method and sources
Each number and rule comes from a source with the date it was checked.
- Sidewall = width × aspect ratio ÷ 100
- Diameter = rim × 25.4 + 2 × sidewall (mm)
- Revs per mile = 63,360 ÷ (π × diameter, in)
- True speed = dial × new diameter ÷ old diameter
- Clearance change = half the diameter change
Numbers are nominal: the tire unloaded, on its measuring rim. Revs per mile published by makers run higher than the formula. “Within 3%” is a rule of thumb tire shops use, not a law. Tire pressure: the placard on your door jamb.
- Nitto: size table (nittotire.com)checked Oct 15, 2026
- Firestone: size table (firestonetire.com)checked Oct 15, 2026
- Toyo: size table (toyotires.com)checked Oct 15, 2026
- Mickey Thompson: size table (mickeythompsontires.com)checked Oct 15, 2026
- 49 CFR 571.139 (FMVSS No. 139), S5.5(d)ecfr.gov · checked Oct 15, 2026
- 49 CFR 571.110 (FMVSS No. 110), S4.3ecfr.gov · checked Oct 15, 2026
Related
Calculators and size classes
- Tire size calculatorTwo sizes: diameter, sidewall, revs and speedometer.
- Compare up to 4 sizesUp to four sizes side by side, drawn to scale.
- Metric ↔ inchesMetric to inches, and 33x12.50R20 to metric.
- Speedometer errorTrue speed after a size change.
- Gear ratio and RPMEngine RPM and the ratio to regear to.
- Wheel offset and pokeBackspacing, poke and inner clearance.
- DOT date codeHow old a tire is, from the DOT number.
- Load index chartLoad index in pounds and kilograms.
- Bolt patternMeasure it, convert inches to mm.
- Rim size and tire fitWhat 17x8 ET35 means, which sizes go on it.
- What fits my carStart from the placard on the door.
- Tire size chartCommon sizes in inches, by rim.