I just got new tires yesterday, but I think I might have a problem. I ordered the 255/45ZR18 BFGoodrich g-Force T/A KDW2's all the way around, but I noticed today that they put 255/40ZR18's on instead. I went to America's Tire Company because they price matched TireRack's prices. The 40's are cheaper at TireRack. How big of a problem is this? Should I get them to price match the cheaper tires they gave me, or have them put on the correct size that I ordered? Even though the tires are smaller in diameter, I am very pleased with how the car handles. It is night and day difference compared to the stockers. Suspension upgrades are next.

 

The 255/40/18 are an overall diamter of 26 inch versus the correct 27 inch of the 255/45/18. The car thus has 1/2 less ground clearance and 1/2 larger fender gaps.

The revs per mile are 801 versus the correct 777 - about 3.1 % so your speedo will be out that much.

It will also reduce your top speed in each gear by 3.1%.

The weight and rim size requirements are different per this chart

http://www.tirerack.com/tires/tires....ce+T%2FA+KDW+2

 

those look tiny! i would get them to put on the tires you wanted, not the ones they decided to give you

 

If you priced and ordered 255/45s, I'd make sure that's what they gave you. Besides, those 255/40s are tiny.

 

I think your tires look alright! The 45 side wall is a little taller but there is no way you are going to see a big difference between the 40 and the 45 to the eye. The smaller tire will throw your speedo off but can be adjusted out with a tuner I beleive. I run 275/40/17 rears. I like the smaller tire because it lowers the gear ratio, Better performance! It will cut your top speed, But how often are you running top speed? I would go back on them and ask for the difference of cost and explain the speedo differance to revamp the cost or get what you ask for if you think you need the 45`s. Did I tell you your car looks great?

 

get the tires you wanted

 

Thanks for the replies everyone, and thanks for the compliment BadSteed! As with everyone else, my car is a work in progress. I like to think that I have been making tasteful mods without taking away the character of the Bullitt.

I have an appointment tomorrow morning to get the 255/45's put on. I must say that the increased acceleration with these tires is a lot of fun though. I'm just not sure it's worth sacrificing the look of the car for.

 

I think that's the right move.

Dave

 

You could always throw a set of 4.10s in there for similar results!

Tim

 

+1

they look small to me and it's not what you ordered. it's a pain now that they're installed but it's their fault, not yours.