SidewallerTire & wheel calculators

225/40R18 vs 235/40R18

235/40R18 is 1.3% taller (+0.31 in) and 0.39 in wider than 225/40R18.

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Close match

235/40R18 is 1.3% taller than 225/40R18. That is inside the ±3% most shops treat as a straight swap.

225/40R18235/40R18Change
Diameter25.09″25.40″+0.31″+1.3%
Width8.86″9.25″+0.39″+4.4%
Sidewall3.54″3.70″+0.16″+4.4%
Circumference78.8″79.8″+1.0″+1.3%
Wheel18″18″Same
Revs per mile804794−10
SideTread
225/40R18235/40R18
Speedometer shows 60 mph60.8mph

Real speed on 235/40R18.

Ground clearance+0.16in

Change in height under the axle.

Width per side+0.20in

On the same wheel, split inboard and outboard.

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225/40R18 or 235/40R18?

Can I use 235/40R18 instead of 225/40R18?

235/40R18 is 1.3% taller than 225/40R18. 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 235/40R18 you are really doing 60.8 mph if the speedometer was set up for 225/40R18. Going the other way, 225/40R18 would make it read 59.3 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.16 in (+4 mm) under the axle.

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