CarSpecsHQ

315/35R22 vs 305/40R22

305/40R22 is outside the ±3% rule as a replacement for 315/35R22: the diameter differs by +3.02%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

22" rim
315/35R22 30.68" · 305/40R22 31.61" · drawn to scale

Side by side

315/35R22305/40R22Difference
Overall diameter30.68"31.61"+0.93" (+3.02%)
Section width315 mm305 mm-10 mm
Sidewall4.34"4.80"+0.46"
Rim22"22"same
Circumference96.4"99.3"+2.9"
Revs per mile657638-19
Ride height——+0.46"
Speedometer reads 60 mph60.061.8+1.8 mph

Speedometer and odometer

020406080100120 reads 60 · actual 61.8 mph

With 305/40R22 on a car calibrated for 315/35R22, the speedometer reads 58.2 mph when you're really doing 60, and the odometer under-counts by 3.0%.

Speedo showsActual speed
30 mph30.9 mph
45 mph46.4 mph
60 mph61.8 mph
70 mph72.1 mph
80 mph82.4 mph

Other sizes close to 315/35R22

Questions

Can I replace 315/35R22 with 305/40R22?

305/40R22 is outside the ±3% rule as a replacement for 315/35R22: the diameter differs by +3.02%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

What's the difference between 315/35R22 and 305/40R22?

305/40R22 is 0.93" taller and 10 mm narrower; the sidewall is +0.46". At an indicated 60 mph you'd actually be doing 61.8 mph.

Will 305/40R22 fit on 315/35R22 wheels?

Both use a 22" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.