Tire RulerWhat changes when you switch to 285/65R18
- Height: +1.54″ (+4.9%), so ground clearance at the axle goes up 0.77″.
- Width: +1.18″ (30 mm). Check inner clearance to the suspension and frame, and the fender liner at full lock.
- Sidewall: +0.77″. A taller sidewall rides a bit softer and protects the wheel off-road.
- Revolutions per mile: 650 → 619. Your gears act about 4.9% taller; at 65 mph in a 0.69 top gear with 3.73s, that’s 1,811 → 1,726 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.
Other comparisons
Frequently asked questions
How much bigger is 285/65R18 than 255/65R18?
285/65R18 is 1.54 inches (4.9%) taller and 1.18 inches wider: 32.6" × 11.2" versus 31.1" × 10.0".
Will 285/65R18 change my speedometer?
Yes, by 4.9%. Going from 255/65R18 to 285/65R18, an indicated 60 mph is about 63.0 mph.
Can I replace 255/65R18 with 285/65R18?
Possibly, but the height difference is over 3%, so check clearance and plan to recalibrate the speedometer. Both fit an 18" wheel; confirm the rim width, load index and clearance for your vehicle.
Do I need to regear going from 255/65R18 to 285/65R18?
It's worth considering. To restore 3.73 gearing you'd need about 3.91 (3.73 or 3.92).