225/40R18 vs 225/45R18
225/45R18 is 3.5% taller (+0.89 in) and the same width than 225/40R18.
225/45R18 is 3.5% taller than 225/40R18. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock.
Real speed on 225/45R18.
Change in height under the axle.
On the same wheel, split inboard and outboard.
Shop 225/45R18 tires
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225/40R18 or 225/45R18?
Can I use 225/45R18 instead of 225/40R18?
225/45R18 is 3.5% taller than 225/40R18. It often still fits, but expect a noticeable speedometer error and check clearance at full steering lock. 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 225/45R18 you are really doing 62.1 mph if the speedometer was set up for 225/40R18. Going the other way, 225/40R18 would make it read 58.0 mph at a real 60.
How much ground clearance does it change?
Half the diameter difference: +0.44 in (+11 mm) under the axle.