255/85R17 vs 275/80R17 tire size comparison

Change either size and everything below updates.

Start from your car make, model, year
Current tire size
/R
xR
New tire size
/R
xR

Width in mm · aspect = sidewall height as a % of width · rim in inches

Flotation (LT) sizes, all in inches: overall diameter × section width, then rim

255/85R17: 34.07″ (865 mm) tall, 10.04″ (255 mm) wide, sidewall 8.53″ (217 mm) — 592 revolutions per mile.

Well within tolerance

+0.75% diameter

The overall diameter changes by less than 1.5%, so speedometer error is negligible and ride height barely moves.

  • 20 mm wider: check inner clearance and that your rims are wide enough.

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Measurement255/85R17275/80R17Diff%
Overall diameter34.07″865 mm34.32″872 mm+0.26″+0.8%
Section width255.0 mm275.0 mm+20.0 mm+7.8%
Sidewall height216.8 mm220.0 mm+3.3 mm+1.5%
Rim diameter17″17″0″0.0%
Circumference107.02″2718 mm107.83″2739 mm+0.80″+0.8%
Revolutions per mileturns per distance; drives the odometer592368 /km588365 /km−4−0.7%
Ride height change——+0.13″ +3.2 mm

Speedometer reading

Speedo shows
60mph
97 km/h
Actual speed
60.5mph
97 km/h

Overlay

255/85R17275/80R17

Plus sizing: 255/85R17 on smaller or bigger wheels

Sizes fitted to cars that keep the overall diameter within 3% of 255/85R17 on a rim one inch smaller or up to two inches bigger, closest first.

RimSizeDiameterChangeCompare
R18 (+1) 285/75R18 34.83″ +2.2% Compare
275/70R18 33.16″ −2.7% Compare
R19 (+2) 265/70R19 33.61″ −1.4% Compare

How to use the tire size calculator

Put your current tire size — width, aspect ratio and rim diameter — into the first form, then your desired size into the second. You’ll get the difference between the new and the old size, plus the speedometer reading difference and your actual speed on the new set. Both metric and flotation (LT inch) sizes are supported.

The calculator helps you decide whether a set of tires and wheels will fit your car. To compare tires by brand and model instead, use our tire comparison tool; to look up factory sizes, browse by car make.

Changing wheels too? The wheel offset calculator shows how far a new wheel width and offset move the tire toward the suspension and the fender.

Reading a tire size

225/45R17
225
Section width in millimetres
45
Aspect ratio — sidewall height as a % of width
R
Radial construction
17
Rim diameter in inches

Full guide to the tire sidewall →