SidewallerTire & wheel calculators

205/70R15 vs 235/45R18

235/45R18 is 0.1% taller (+0.03 in) and 1.18 in wider than 205/70R15.

OK
Close match

235/45R18 is 0.1% taller than 205/70R15. That is inside the ±3% most shops treat as a straight swap.

205/70R15235/45R18Change
Diameter26.30″26.33″+0.03″+0.1%
Width8.07″9.25″+1.18″+14.6%
Sidewall5.65″4.16″−1.49″−26.3%
Circumference82.6″82.7″+0.1″+0.1%
Wheel15″18″+3″
Revs per mile767766−1
SideTread
205/70R15235/45R18
Speedometer shows 60 mph60.1mph

Real speed on 235/45R18.

Ground clearance+0.01in

Change in height under the axle.

Width per side+0.59in

On the same wheel, split inboard and outboard.

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205/70R15 or 235/45R18?

Can I use 235/45R18 instead of 205/70R15?

235/45R18 is 0.1% taller than 205/70R15. 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 235/45R18 you are really doing 60.1 mph if the speedometer was set up for 205/70R15. Going the other way, 205/70R15 would make it read 59.9 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.01 in (+0 mm) under the axle.

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