Tire RulerWhat changes when you switch to 305/50R20
- Height: +0.10″ (+0.3%), so ground clearance stays practically the same.
- Width: +1.18″ (30 mm). Check inner clearance to the suspension and frame, and the fender liner at full lock.
- Sidewall: +0.05″. A taller sidewall rides a bit softer and protects the wheel off-road.
- Revolutions per mile: 632 → 630. Your gears act about 0.3% taller; at 65 mph in a 0.69 top gear with 3.73s, that’s 1,762 → 1,757 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 305/50R20 than 275/55R20?
305/50R20 is 0.10 inches (0.3%) taller and 1.18 inches wider: 32.0" × 12.0" versus 31.9" × 10.8".
Will 305/50R20 change my speedometer?
Yes, by 0.3%. Going from 275/55R20 to 305/50R20, an indicated 60 mph is about 60.2 mph.
Can I replace 275/55R20 with 305/50R20?
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 275/55R20 to 305/50R20?
Usually not for a 0.3% change. With 3.73 gears, the 305/50R20 acts like 3.72.