tireheight.com255/70R18 vs 285/70R17
285/70R17 is 0.7″ taller than 255/70R18 on average, going by the heights their makers list (32.1″ vs 32.9″). On paper the gap is 0.65″.
What changes
Going from 255/70R18 to 285/70R17.
Lift is half the height difference, since the axle sits at the middle of the tire. The speedometer figure assumes it was set for 255/70R18 and uses the revolutions per mile the makers publish: at an indicated 60 mph you'd be doing 61.4 mph.
Side by side
| 255/70R18 | 285/70R17 | Difference | |
|---|---|---|---|
| Listed height ″ | 32.09–32.30 | 32.70–33.15 | +0.75 |
| Size code height ″ | 32.06 | 32.71 | +0.65 |
| Height under load ″ | 31.1 | 31.8 | +0.7 |
| Width ″ | 10.04 | 11.22 | +1.18 |
| Listed width ″ | 10.2–10.5 | 11.4–11.6 | +1.3 |
| Sidewall ″ | 7.03 | 7.85 | +0.83 |
| Wheel ″ | 18 | 17 | −1 |
| Weight lb | 35.3–52.3 | 46.0–65.7 | +15.4 |
| Tread depth /32″ | 9–15 | 13–19 | +4.0 |
| Tires listed | 14 | 36 |
Tires sold in both sizes
The same model in each size, by the heights the maker lists. Averages where a model comes in several load ranges.
| Tire | 255/70R18 ″ | 285/70R17 ″ | Taller by | Heavier by |
|---|---|---|---|---|
| BFGoodrich All-Terrain T/A KO2 | 32.10 | 32.80 | +0.70″ | −0.1 lb |
| BFGoodrich All-Terrain T/A KO3 | 32.10 | 32.80 | +0.70″ | +3.6 lb |
| BFGoodrich Trail-Terrain T/A | 32.10 | 32.80 | +0.70″ | +3.6 lb |
| BFGoodrich Trail-Terrain T/A+ | 32.10 | 32.80 | +0.70″ | +2.9 lb |
| General Grabber A/TX | 32.10 | 32.70 | +0.60″ | +12.4 lb |
| General Grabber APT | 32.10 | 32.70 | +0.60″ | +18.1 lb |
| Michelin Defender LTX M/S 2 | 32.10 | 32.80 | +0.70″ | +13.6 lb |
| Toyo Open Country A/T III | 32.09 | 32.81 | +0.73″ | +12.9 lb |
| Toyo Open Country H/T II | 32.09 | 32.76 | +0.67″ | +12.4 lb |
Questions about 255/70R18 vs 285/70R17
How much taller is 285/70R17 than 255/70R18?
0.75″ on average, going by the heights tire makers list: 255/70R18 tires are listed at 32.09–32.30″ and 285/70R17 at 32.70–33.15″. The size codes work out to 32.06″ and 32.71″, a 0.65″ difference.
How much lift does 285/70R17 give over 255/70R18?
The tire's radius grows by 0.37″, so the axle sits about 0.37″ higher, and the top of the tread comes 0.37″ closer to the fender. 285/70R17 is also 1.18″ wider on paper, 0.59″ per side on the same wheel. Whether it fits depends on your vehicle, lift and wheel offset.
Will my speedometer be off with 285/70R17 instead of 255/70R18?
Yes. If it's set for 255/70R18, it will read about 2.3% slow: at an indicated 60 mph you'll be doing 61.4 mph. Worked out from the revolutions per mile the makers publish.
Can 285/70R17 go on the same wheel as 255/70R18?
No. 255/70R18 fits a 18-inch wheel and 285/70R17 a 17-inch wheel.