What is the MPG difference between 18" and 20" tires on 2500 diesels
Nothing you will ever notice. Just because the rims are lager the outside diameter of both tires are very close to the same. Look at the size difference in the sidewalls of both tires. The 20's have less sidewall than the 18's. I hope this makes sense to you. Its a little hard to explain over a post.
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