CarSpecsHQ

245/45R20 vs 315/35R20

315/35R20 is a safe swap for 245/45R20 by the usual ±3% rule: the diameter differs by 0.00%.

20" rim
245/45R20 28.68" · 315/35R20 28.68" · drawn to scale

Side by side

245/45R20315/35R20Difference
Overall diameter28.68"28.68"0.00" (0.00%)
Section width245 mm315 mm+70 mm
Sidewall4.34"4.34"0.00"
Rim20"20"same
Circumference90.1"90.1"0.0"
Revs per mile7037030
Ride height——0.00"
Speedometer reads 60 mph60.060.00.0 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.0 mph

With 315/35R20 on a car calibrated for 245/45R20, the speedometer reads 60.0 mph when you're really doing 60, and the odometer over-counts by 0.0%.

Speedo showsActual speed
30 mph30.0 mph
45 mph45.0 mph
60 mph60.0 mph
70 mph70.0 mph
80 mph80.0 mph

Other sizes close to 245/45R20

Questions

Can I replace 245/45R20 with 315/35R20?

315/35R20 is a safe swap for 245/45R20 by the usual ±3% rule: the diameter differs by 0.00%.

What's the difference between 245/45R20 and 315/35R20?

315/35R20 is 0.00" taller and 70 mm wider; the sidewall is 0.00". At an indicated 60 mph you'd actually be doing 60.0 mph.

Will 315/35R20 fit on 245/45R20 wheels?

Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 315 mm tire and the fender clearance.