AutoX tire width

So I have set of 18x8.5 Evo X wheels that need tires. These are going to be my auto x wheels and I need to choose a set of tires. I am just looking at a nice sticky summer tire like a Hankook Ventus Evo that are available with free shipping from Amazon Prime. (A huge savings for being on Hawaii)

Question is, should I run a 245/40/18 like evos do stock, or can I go up to a 255 width? Will there be adverse handling characteristics running the wider tire due to sidewall flex? Should I look at a tire more aggressive than a summer street tire? Not trying to break the bank. I'm a newbie in autox.
The auto x here is all in the stadium parking lot, so not much for wide open space and straight aways. Tons of turns!

Thanks for your advice

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You can run a 255/35/18 on those EVO rims just fine. Just get your tire pressures right and a nice alignment and you will do fine.

Since its your first time the Hankooks would be a good tire to learn on.

Think 35 is better than 40 or is that just the more correct size to keep it close to stock height?

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I wouldn't want to run much taller than stock. More chance of running into rubbing issues. Check tirerack.com specs on the sizes to help make your choice.

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Originally Posted by jonezj

Think 35 is better than 40 or is that just the more correct size to keep it close to stock height?

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When you increase tire width, you need to decrease sidewall height, to maintain close to stock diameter. This is because sidewall height is a percentage of tread width.

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Originally Posted by jonezj

Think 35 is better than 40 or is that just the more correct size to keep it close to stock height?

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As the others have said changing 35 to 40 changes the height.

Stock size on a VR4 is 245/45/17

245 is the section width in millimeters. To convert that to inches you would divide it by 25.4.
45 is percentage of diameter that is the sidewall height.
17 is, obviously, the rim diameter

The math formula to figure out the overall diameter would be the following:

((245/25.4) * .45) * 2) + 17 = 25.68

Now if you do the same for the 255/35/18 you'd get

((255/25.4) * .35) * 2) + 18 = 25.02

255/40/18 would be

((255/25.4) * .40) * 2) + 18 = 26.03

If you want wider you could do 265/35/18

((265/25.4) * .35) * 2) + 18 = 25.3

Thank you so much for that breakdown. In terms of sidewall stiffness and cornering performance, how would a 265/35 compare to 255/35 or 245/40 on an 18x8.5 Evo wheel?
I like wider, but don't want to sacrifice performance for autox.

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Considering overall height difference between the 265/35 and 265/35 is .27" you are talking only a difference of .135" in sidewall height. That's roughly 1/8". The height difference will have less effect on sidewall stiffness than that of the actual make up of the tire.

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Originally Posted by stealthee

Considering overall height difference between the 265/35 and 265/35 is .27" you are talking only a difference of .135" in sidewall height. That's roughly 1/8". The height difference will have less effect on sidewall stiffness than that of the actual make up of the tire.

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Although this is true, you must also keep in mind that 255 is the maximum recommended tread width for an 8.5" rim.

Exceeding 255 could be considered a "stretched" fitment which is generally accepted as an unsafe fitment.

That's what I was trying to get at. I thought 265 would be too much for 8.5s. I always thought of "stretched" as the opposite though. Putting a narrow tire on a wider wheel like them stance fellas do. Lol

Thanks again for the great input.

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