Tire Size Box

185/35R17 vs 185/45R17

185/45R17 compared with 185/35R17

+6.6% diameter, 0.0" width

185/45R17 is 23.56" tall vs 22.10". More than the 3% rule of thumb, so check carefully before switching.

22.1"17" rim2.5"7.3" wide
185/35R17 (solid) compared with 185/45R17 (dashed outline), drawn to scale

With 185/45R17 tires, when your speedometer says 60 mph you are really going

64.0 mph

185/45R17 is +1.46 inches (+6.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

185/35R17185/45R17Difference%
Overall diameter22.10"23.56"+1.46"+6.6%
Section width7.28"7.28"0.00"0.0%
Sidewall height2.55"3.28"+0.73"+28.6%
Circumference69.42"74.00"+4.58"+6.6%
Revolutions per mile912.6856.2−56.4−6.2%

Speedometer difference

If your vehicle came with 185/35R17 and you fit 185/45R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.3 mph+1.3 mph
30 mph32.0 mph+2.0 mph
40 mph42.6 mph+2.6 mph
50 mph53.3 mph+3.3 mph
60 mph64.0 mph+4.0 mph
65 mph69.3 mph+4.3 mph
70 mph74.6 mph+4.6 mph
75 mph79.9 mph+4.9 mph
80 mph85.3 mph+5.3 mph

Each size on its own

Questions

Which is bigger, 185/35R17 or 185/45R17?
185/45R17 is taller by 1.46 inches (23.56" vs 22.10"). 185/35R17 is the same width.
Can I replace 185/35R17 with 185/45R17?
It is not recommended without checking carefully. The diameter difference is +6.6%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 185/45R17 change my speedometer?
When your speedometer reads 60 mph with 185/45R17 fitted (calibrated for 185/35R17), your real speed is 64.0 mph. Your odometer will under-count miles by about 6.6%.
Will 185/45R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.73 inches of ground clearance at the axle.

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