SidewallerTire & wheel calculators

275/65R18 vs 33x12.50R18

33x12.50R18 is 2.9% taller (+0.93 in) and 1.67 in wider than 275/65R18.

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Close match

33x12.50R18 is 2.9% taller than 275/65R18. That is inside the ±3% most shops treat as a straight swap.

275/65R1833x12.50R18Change
Diameter32.07″33.00″+0.93″+2.9%
Width10.83″12.50″+1.67″+15.5%
Sidewall7.04″7.50″+0.46″+6.6%
Circumference100.8″103.7″+2.9″+2.9%
Wheel18″18″Same
Revs per mile629611−18
SideTread
275/65R1833x12.50R18
Speedometer shows 60 mph61.7mph

Real speed on 33x12.50R18.

Ground clearance+0.46in

Change in height under the axle.

Width per side+0.84in

On the same wheel, split inboard and outboard.

Shop 33x12.50R18 tires

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275/65R18 or 33x12.50R18?

Can I use 33x12.50R18 instead of 275/65R18?

33x12.50R18 is 2.9% taller than 275/65R18. 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 33x12.50R18 you are really doing 61.7 mph if the speedometer was set up for 275/65R18. Going the other way, 275/65R18 would make it read 58.3 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.46 in (+12 mm) under the axle.

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