SidewallerTire & wheel calculators

285/35R21 vs 265/40R21

265/40R21 is 1.7% taller (+0.49 in) and 0.79 in narrower than 285/35R21.

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Close match

265/40R21 is 1.7% taller than 285/35R21. That is inside the ±3% most shops treat as a straight swap.

285/35R21265/40R21Change
Diameter28.85″29.35″+0.49″+1.7%
Width11.22″10.43″−0.79″−7.0%
Sidewall3.93″4.17″+0.25″+6.3%
Circumference90.6″92.2″+1.5″+1.7%
Wheel21″21″Same
Revs per mile699687−12
SideTread
285/35R21265/40R21
Speedometer shows 60 mph61.0mph

Real speed on 265/40R21.

Ground clearance+0.25in

Change in height under the axle.

Width per side−0.39in

On the same wheel, split inboard and outboard.

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285/35R21 or 265/40R21?

Can I use 265/40R21 instead of 285/35R21?

265/40R21 is 1.7% taller than 285/35R21. 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 265/40R21 you are really doing 61.0 mph if the speedometer was set up for 285/35R21. Going the other way, 285/35R21 would make it read 59.0 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.25 in (+6 mm) under the axle.

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