SidewallerTire & wheel calculators

265/45R20 vs 255/50R20

255/50R20 is 2.2% taller (+0.65 in) and 0.39 in narrower than 265/45R20.

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Close match

255/50R20 is 2.2% taller than 265/45R20. That is inside the ±3% most shops treat as a straight swap.

265/45R20255/50R20Change
Diameter29.39″30.04″+0.65″+2.2%
Width10.43″10.04″−0.39″−3.8%
Sidewall4.69″5.02″+0.32″+6.9%
Circumference92.3″94.4″+2.0″+2.2%
Wheel20″20″Same
Revs per mile686671−15
SideTread
265/45R20255/50R20
Speedometer shows 60 mph61.3mph

Real speed on 255/50R20.

Ground clearance+0.32in

Change in height under the axle.

Width per side−0.20in

On the same wheel, split inboard and outboard.

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265/45R20 or 255/50R20?

Can I use 255/50R20 instead of 265/45R20?

255/50R20 is 2.2% taller than 265/45R20. 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 255/50R20 you are really doing 61.3 mph if the speedometer was set up for 265/45R20. Going the other way, 265/45R20 would make it read 58.7 mph at a real 60.

How much ground clearance does it change?

Half the diameter difference: +0.32 in (+8 mm) under the axle.

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