18's or 19's....

[tjm73]

In the attached photos (which I found on a different board) the owner claims these are 275/40R19 Pirellli P-Zero Nero A/S, like I am looking at, on FRPP 19x9 GT500 wheels. Knowing that a 9" wheel is really 10" wide at the outside to outside measurement and that the P-Zero is spec'd at approximately 11" wide with just over 10" of tread width, these do not look right. This looks like a 255 on a 9" or the 275 on a 10" wheel.

This is the look I do not want. This looks stretched to me.

 

[Norm Peterson]

Truth be told, there isn't a lot of visual difference between a 275/40 and a 255/45 when they are both mounted on the same width wheels. This has to do with the fact that the 275/40 is measured on a wider rim to begin with, and won't "gain" the same amount of section width that the 255/45 will.

There isn't enough sidewall height in a 285 wide tire in 40 or lower profile to be properly squeezed down onto 9" wide wheels. You'd have to take a 285-wide tire up to 45 profile or taller.


Norm

 

[Norm Peterson]

A 275/40 where the sidewall sticks 3/8" outside the wheel is about the most you can expect here.


Norm

 

[tjm73]

I will most likely buy the P-Zero since it has the best balance of all factors that matter to me and it will fit how it fits.

Another member here has 18x9 with 45mm offset and 275/40R18's and the shape of the sidewall on the wheel and the location of the wheel under the car is very acceptable to me. Here's a picture of it. If I am close to this, but with a 19" wheel, I will be quite pleased.

 

[Drex]

What size tires are you running? I tried looking to see if you posted any pics. Didn't see anything.

I measured my rims for a outside-to-outside measurement and they measure 10 1/16". So I am looking for tires that won't look stretched on them. Square would be perfect. My car's a total driver so I'm looking at 275/40R19 Pirelli P-Zero Nero All Seasons so I can 4 wheel rotate. If not those I may go with Hankook Ventus V12's in 275/40R19 or Kumho Ecsta SPT in 285/35R19.

Tires an wheels are on order so just waiting for the shipment. It may take awhile being in Germany, although everyone here likes to use Tire Rack and have given me good reports on their shipping time.

I am staggering 275/40/19 and 255/40/19 on those wheels I linked earlier. They are 9" wheels. I am going to order those lugs from Summit: thx for the tip! Pictures will be posted when I install the new wheels/tires.

 

[Drex]

Forgot; went with the Hankook ventos V12's

 

[tjm73]

Truth be told, there isn't a lot of visual difference between a 275/40 and a 255/45 when they are both mounted on the same width wheels. This has to do with the fact that the 275/40 is measured on a wider rim to begin with, and won't "gain" the same amount of section width that the 255/45 will.

Been thinking about this. A 275/40 has 4.33" of sidewall and the 255/45 has 4.51" of sidewall. Barely more than 3/16" more sidewall. I really don't see that making a big difference. I also don't know where the 255/45 came from. If anyone is going to run a staggered 19" setup they are running 255/40R19's.

 

[Norm Peterson]

255/45 came from the way this thread started out, and because they're a closer tire OD match to the 275/40. Choosing between those two sizes in 18" does come up at least occasionally, so it's a fair comparison as far as choosing a 275 over a 255 to mention that the 275 isn't going to be much wider in the actual installation if the wheel width is held constant.

The sidewall height issue for 9" rims comes in at the 285-wide tire size, where a line has to be drawn somewhere and it happens to be between 45 profile (being OK'ed for 9" rims by people with more information and detail technical tire knowledge than I have) and 40 (which isn't).

What I do know about tires and rims that are narrower than the "measuring width" has to do with not only the amount of heat generated, but specifically where in the sidewall it tends to concentrate. Sidewalls generally are not uniformly resistant to this as you move from the shoulder up to the bead, so this effect actually does matter to some extent. And that was straight from the horse's mouth, as the saying goes.


Norm