Tire RulerWhat changes when you switch to 275/55R20
- Height: +0.87″ (+2.8%), so ground clearance at the axle goes up 0.43″.
- Width: +0.79″ (20 mm). Check inner clearance to the suspension and frame, and the fender liner at full lock.
- Sidewall: +0.43″. A taller sidewall rides a bit softer and protects the wheel off-road.
- Revolutions per mile: 650 → 632. Your gears act about 2.8% taller; at 65 mph in a 0.69 top gear with 3.73s, that’s 1,811 → 1,762 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 275/55R20 than 255/55R20?
275/55R20 is 0.87 inches (2.8%) taller and 0.79 inches wider: 31.9" × 10.8" versus 31.0" × 10.0".
Will 275/55R20 change my speedometer?
Yes, by 2.8%. Going from 255/55R20 to 275/55R20, an indicated 60 mph is about 61.7 mph.
Can I replace 255/55R20 with 275/55R20?
Often, yes: the height difference is within the ±3% most tire shops accept. Both fit a 20" wheel; confirm the rim width, load index and clearance for your vehicle.
Do I need to regear going from 255/55R20 to 275/55R20?
Usually not for a 2.8% change. With 3.73 gears, the 275/55R20 acts like 3.63.