Tire RulerWhat changes when you switch to 275/55R20
- Height: +0.33″ (+1.1%), so ground clearance at the axle goes up 0.17″.
- Width: +1.18″ (30 mm). Check inner clearance to the suspension and frame, and the fender liner at full lock.
- Sidewall: +0.17″. A taller sidewall rides a bit softer and protects the wheel off-road.
- Revolutions per mile: 639 → 632. Your gears act about 1.1% taller; at 65 mph in a 0.69 top gear with 3.73s, that’s 1,781 → 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.
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Frequently asked questions
How much bigger is 275/55R20 than 245/60R20?
275/55R20 is 0.33 inches (1.1%) taller and 1.18 inches wider: 31.9" × 10.8" versus 31.6" × 9.6".
Will 275/55R20 change my speedometer?
Yes, by 1.1%. Going from 245/60R20 to 275/55R20, an indicated 60 mph is about 60.6 mph.
Can I replace 245/60R20 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 245/60R20 to 275/55R20?
Usually not for a 1.1% change. With 3.73 gears, the 275/55R20 acts like 3.69.