Tire Size Box

275/35R17 vs 275/45R17

275/45R17 compared with 275/35R17

+8.8% diameter, 0.0" width

275/45R17 is 26.74" tall vs 24.58". More than the 3% rule of thumb, so check carefully before switching.

24.6"17" rim3.8"10.8" wide
275/35R17 (solid) compared with 275/45R17 (dashed outline), drawn to scale

With 275/45R17 tires, when your speedometer says 60 mph you are really going

65.3 mph

275/45R17 is +2.17 inches (+8.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/35R17275/45R17Difference%
Overall diameter24.58"26.74"+2.17"+8.8%
Section width10.83"10.83"0.00"0.0%
Sidewall height3.79"4.87"+1.08"+28.6%
Circumference77.22"84.02"+6.80"+8.8%
Revolutions per mile820.6754.1−66.4−8.1%

Speedometer difference

If your vehicle came with 275/35R17 and you fit 275/45R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.8 mph+1.8 mph
30 mph32.6 mph+2.6 mph
40 mph43.5 mph+3.5 mph
50 mph54.4 mph+4.4 mph
60 mph65.3 mph+5.3 mph
65 mph70.7 mph+5.7 mph
70 mph76.2 mph+6.2 mph
75 mph81.6 mph+6.6 mph
80 mph87.0 mph+7.0 mph

Each size on its own

Questions

Which is bigger, 275/35R17 or 275/45R17?
275/45R17 is taller by 2.17 inches (26.74" vs 24.58"). 275/35R17 is the same width.
Can I replace 275/35R17 with 275/45R17?
It is not recommended without checking carefully. The diameter difference is +8.8%, 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 275/45R17 change my speedometer?
When your speedometer reads 60 mph with 275/45R17 fitted (calibrated for 275/35R17), your real speed is 65.3 mph. Your odometer will under-count miles by about 8.8%.
Will 275/45R17 lift my vehicle?
Ride height changes by half the diameter difference: +1.08 inches of ground clearance at the axle.

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