285/70R17 is 0.2″ taller than 265/70R18 on average, going by the heights their makers list (32.7″ vs 32.9″). On paper the gap is 0.10″.
Going from 265/70R18 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 265/70R18 and uses the revolutions per mile the makers publish: at an indicated 60 mph you'd be doing 60.3 mph.
| 265/70R18 | 285/70R17 | Difference | |
|---|---|---|---|
| Listed height ″ | 32.60–33.03 | 32.70–33.15 | +0.19 |
| Size code height ″ | 32.61 | 32.71 | +0.10 |
| Height under load ″ | 31.7 | 31.8 | +0.1 |
| Width ″ | 10.43 | 11.22 | +0.79 |
| Listed width ″ | 10.6–10.7 | 11.4–11.6 | +0.8 |
| Sidewall ″ | 7.30 | 7.85 | +0.55 |
| Wheel ″ | 18 | 17 | −1 |
| Weight lb | 37.0–60.4 | 46.0–65.7 | +8.5 |
| Tread depth /32″ | 10–19 | 13–19 | +2.3 |
| Tires listed | 33 | 36 |
The same model in each size, by the heights the maker lists. Averages where a model comes in several load ranges.
| Tire | 265/70R18 ″ | 285/70R17 ″ | Taller by | Heavier by |
|---|---|---|---|---|
| BFGoodrich All-Terrain T/A KO3 | 32.60 | 32.80 | +0.20″ | +0.8 lb |
| BFGoodrich HD-Terrain T/A KT | 32.60 | 32.80 | +0.20″ | +2.2 lb |
| BFGoodrich Trail-Terrain T/A | 32.60 | 32.80 | +0.20″ | +2.3 lb |
| BFGoodrich Trail-Terrain T/A+ | 32.60 | 32.80 | +0.20″ | +2.0 lb |
| General Grabber A/TX | 32.60 | 32.70 | +0.10″ | +5.9 lb |
| General Grabber APT | 32.60 | 32.70 | +0.10″ | +15.9 lb |
| General Grabber X3 | 32.60 | 32.70 | +0.10″ | +4.2 lb |
| Michelin Defender LTX M/S 2 | 32.60 | 32.80 | +0.20″ | +6.7 lb |
| Mickey Thompson Baja Legend EXP | 32.90 | 33.10 | +0.20″ | +3.0 lb |
| Toyo M-55 | 33.03 | 33.15 | +0.12″ | +0.4 lb |
| Toyo M655 | 33.03 | 33.07 | +0.04″ | +1.5 lb |
| Toyo Open Country A/T III | 32.64 | 32.81 | +0.18″ | +5.1 lb |
| Toyo Open Country C/T | 32.87 | 32.99 | +0.12″ | +4.7 lb |
| Toyo Open Country H/T II | 32.64 | 32.76 | +0.12″ | +10.4 lb |
| Toyo Open Country M/T | 32.87 | 32.99 | +0.12″ | +3.8 lb |
| Toyo Open Country R/T Trail | 32.62 | 32.76 | +0.14″ | +5.3 lb |
| Toyo Open Country WLT1 | 32.64 | 32.84 | +0.20″ | +7.7 lb |
0.19″ on average, going by the heights tire makers list: 265/70R18 tires are listed at 32.60–33.03″ and 285/70R17 at 32.70–33.15″. The size codes work out to 32.61″ and 32.71″, a 0.10″ difference.
Almost none: the tire's radius changes by 0.10″. 285/70R17 is also 0.79″ wider on paper, 0.39″ per side on the same wheel. Whether it fits depends on your vehicle, lift and wheel offset.
Barely: about 0.4% slow.
No. 265/70R18 fits a 18-inch wheel and 285/70R17 a 17-inch wheel.