275/55R20 vs 275/60R20: Tire Size Comparison

275/55R20 has an overall diameter of 31.91 in (810.5 mm). 275/60R20 has an overall diameter of 32.99 in (838.0 mm), a difference of 1.08 in (27.5 mm) (3.39%). Both sizes mount on the same 20-inch wheel diameter at the same section width; 275/60R20 has a taller sidewall than 275/55R20 because of its higher aspect ratio (60 vs 55).

Speedometer effect

Because 275/60R20 has a larger overall diameter, a speedometer calibrated for 275/55R20 would under-read once 275/60R20 is fitted: an indicated 60 mph corresponds to about 62.0 mph actual, using the ratio of the two diameters (32.99 in (838.0 mm) / 31.91 in (810.5 mm)). This is the sizes' geometry only, not a manufacturer-measured rolling diameter or a specific vehicle's speedometer calibration.

The table assumes the speedometer is set for 275/55R20 and nothing else changes. Actual speed is indicated speed multiplied by the ratio of the two diameters. The odometer follows the same ratio: after 1,000 indicated miles on 275/60R20, the vehicle has covered about 1034 miles.

Same width, taller sidewall

Both sizes start with 275, so the nominal section width is the same: 10.83 in (275.0 mm). The only number that changes is the aspect ratio, 55 against 60. The aspect ratio is the sidewall height as a percentage of the width. Five extra points on the same 275-millimeter width add 0.54 in (13.8 mm) to each sidewall.

A tire has a sidewall above the wheel and one below it, so the overall diameter grows by twice that amount: 1.08 in (27.5 mm). That is a change of 3.39% from 275/55R20, which is more than the 3% that many tire guides use as a point to stop and check the vehicle manual. The wheel stays the same 20-inch diameter, so all of the change is rubber.

What changes on the road

The taller tire covers more ground per turn. Its circumference is 3.40 in (86.4 mm) longer, and it turns 20.7 fewer times per mile. Anything that counts wheel turns reads low after the change: the speedometer, the odometer and the trip computer's fuel figures.

The axle sits higher by half the diameter change, about 0.54 in (13.8 mm), before the tire is loaded. That is a small gain in ground clearance under the axle. It is not a measured value; a loaded tire flattens at the bottom and the real figure is lower.

Overall gearing becomes slightly taller in the same proportion as the diameter. The engine turns a little slower at a given road speed, and the vehicle pulls a little less hard from a stop. The effective gear ratio tool shows the change for a specific axle ratio.

Check before you buy

A shared width and wheel size do not mean the taller tire fits. The larger diameter needs more room at full steering lock and when the suspension compresses. Check the space at the inner fender liner, the upper control arm and the front bumper cover.

Check the load index and speed rating of the exact tire you plan to buy against the tire placard on the driver's door jamb. Two tires in the same size can carry different loads. If the vehicle came with P-metric tires and the replacement is an LT tire, the inflation pressure and load tables are different.

Electronic systems use wheel speed. On many modern vehicles the speedometer can be recalibrated with a dealer tool or an aftermarket programmer. If it is recalibrated for 275/60R20, do not apply the correction in the table above a second time.

Frequently asked questions

Is 275/60R20 taller than 275/55R20?

Yes. It is 1.08 in (27.5 mm) taller in overall diameter, because its sidewall is 0.54 in (13.8 mm) taller on each side of the wheel.

Will 275/60R20 fit on the same wheel?

Both sizes use a 20-inch wheel and the same nominal width, so the bead diameter matches. Whether the taller tire clears the body and suspension depends on the vehicle, and the approved rim width depends on the exact tire. Check both before buying.

How far off will my speedometer be?

At an indicated 60 mph, the calculated actual speed is 62.0 mph if the speedometer was set for 275/55R20. Use the speedometer error tool for other speeds.

Does the taller tire ride softer?

The taller sidewall has more room to flex, but ride also depends on the tire's construction, pressure and load. This page has no measured ride data.

See the 275/55R20 dimensions in inches, the 275/60R20 dimensions in inches, or factory tire sizes by vehicle.

Sources and limits

Every figure on this page comes from the two tire sizes entered, computed by this site's geometry engine -- not from a manufacturer specification or a claim that either size is interchangeable on any particular vehicle or wheel well. Check your vehicle's owner's manual and the wheel manufacturer's fitment guidance before changing tire size. Full limits are covered on the site disclaimer page. Compare your own sizes with the tire size calculator.

Reference tables: Load index chart and Speed rating chart.