245/75R17 vs 255/70R17 tire size comparison

Change either size and everything below updates.

Start from your car make, model, year

Make Model Year

Width/AspectRRim

DiameterxWidthRRim

Width/AspectRRim

DiameterxWidthRRim

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

Well within tolerance

−1.31% diameter

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

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

Tires in 255/70R17

Check price on Amazon · 255/70R17 Best-rated 255/70R17 tires

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Measurement	245/75R17	255/70R17	Diff	%
Overall diameter	31.47″799 mm	31.06″789 mm	−0.41″	−1.3%
Section width	245.0 mm	255.0 mm	+10.0 mm	+4.1%
Sidewall height	183.8 mm	178.5 mm	−5.3 mm	−2.9%
Rim diameter	17″	17″	0″	0.0%
Circumference	98.86″2511 mm	97.56″2478 mm	−1.30″	−1.3%
Revolutions per mileturns per distance; drives the odometer	641398 /km	649404 /km	+9	+1.3%
Ride height change	—	—	−0.21″ −5.2 mm

Speedometer reading

Speedo shows

60mph

97 km/h

Actual speed

59.2mph

95 km/h

Overlay

245/75R17255/70R17

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.