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245/40R17 vs 315/35R17

315/35R17 is outside the ±3% rule as a replacement for 245/40R17: the diameter differs by +3.90%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

17" rim
245/40R17 24.72" · 315/35R17 25.68" · drawn to scale

Side by side

245/40R17315/35R17Difference
Overall diameter24.72"25.68"+0.96" (+3.90%)
Section width245 mm315 mm+70 mm
Sidewall3.86"4.34"+0.48"
Rim17"17"same
Circumference77.6"80.7"+3.0"
Revs per mile816785-31
Ride height——+0.48"
Speedometer reads 60 mph60.062.3+2.3 mph

Speedometer and odometer

020406080100120 reads 60 · actual 62.3 mph

With 315/35R17 on a car calibrated for 245/40R17, the speedometer reads 57.7 mph when you're really doing 60, and the odometer under-counts by 3.9%.

Speedo showsActual speed
30 mph31.2 mph
45 mph46.8 mph
60 mph62.3 mph
70 mph72.7 mph
80 mph83.1 mph

Other sizes close to 245/40R17

Questions

Can I replace 245/40R17 with 315/35R17?

315/35R17 is outside the ±3% rule as a replacement for 245/40R17: the diameter differs by +3.90%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

What's the difference between 245/40R17 and 315/35R17?

315/35R17 is 0.96" taller and 70 mm wider; the sidewall is +0.48". At an indicated 60 mph you'd actually be doing 62.3 mph.

Will 315/35R17 fit on 245/40R17 wheels?

Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 315 mm tire and the fender clearance.