SidewallerTire & wheel calculators

275/35R18 vs 245/45R17

245/45R17 is 0.4% taller (+0.10 in) and 1.18 in narrower than 275/35R18.

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Close match

245/45R17 is 0.4% taller than 275/35R18. That is inside the ±3% most shops treat as a straight swap.

275/35R18245/45R17Change
Diameter25.58″25.68″+0.10″+0.4%
Width10.83″9.65″−1.18″−10.9%
Sidewall3.79″4.34″+0.55″+14.5%
Circumference80.4″80.7″+0.3″+0.4%
Wheel18″17″−1″
Revs per mile788785−3
SideTread
275/35R18245/45R17
Speedometer shows 60 mph60.2mph

Real speed on 245/45R17.

Ground clearance+0.05in

Change in height under the axle.

Width per side−0.59in

On the same wheel, split inboard and outboard.

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275/35R18 or 245/45R17?

Can I use 245/45R17 instead of 275/35R18?

245/45R17 is 0.4% taller than 275/35R18. That is inside the ±3% most shops treat as a straight swap. Also match or beat the original load index and speed rating, and check that the wheel width suits the new tire.

Will my speedometer be off?

At an indicated 60 mph on 245/45R17 you are really doing 60.2 mph if the speedometer was set up for 275/35R18. Going the other way, 275/35R18 would make it read 59.8 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.05 in (+1 mm) under the axle.

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