Tire RulerWhat changes when you switch to 275/70R18
- Height: +0.57″ (+1.8%), so ground clearance at the axle goes up 0.29″.
- Width: −0.39″ (-10 mm). Check inner clearance to the suspension and frame, and the fender liner at full lock.
- Sidewall: +0.29″. A taller sidewall rides a bit softer and protects the wheel off-road.
- Revolutions per mile: 619 → 608. Your gears act about 1.8% taller; at 65 mph in a 0.69 top gear with 3.73s, that’s 1,726 → 1,696 RPM.
Sizes are theoretical, from the sidewall code. The same size can differ by a few tenths of an inch between brands and tread patterns; check the maker’s spec sheet for the exact model.
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Frequently asked questions
How much bigger is 275/70R18 than 285/65R18?
275/70R18 is 0.57 inches (1.8%) taller and 0.39 inches narrower: 33.2" × 10.8" versus 32.6" × 11.2".
Will 275/70R18 change my speedometer?
Yes, by 1.8%. Going from 285/65R18 to 275/70R18, an indicated 60 mph is about 61.1 mph.
Can I replace 285/65R18 with 275/70R18?
Often, yes: the height difference is within the ±3% most tire shops accept. Both fit an 18" wheel; confirm the rim width, load index and clearance for your vehicle.
Do I need to regear going from 285/65R18 to 275/70R18?
Usually not for a 1.8% change. With 3.73 gears, the 275/70R18 acts like 3.67.