255 35 18's on my SVX
 

In our quest to get enough traction on our test car for ECUtune SVX Stage II, my svx, we got the 255 35 18's installed today. They fit awesome. I can say without a doubt that this is the best wheel and tire size combo for the svx. You can only fit this wide of a tire on this size wheel (8 inch wide +49 offset)so it's an expensive combo but what can I say--it's the way to go. They completely fill the wheel well while not being in any danger of rubbing, none of that negative camber stuff to try to make them fit where they don't. It's raining out and getting dark so I couldn't take many pictures but I snapped a couple off real quick.


http://www.ecutune.com/posts/255-1.jpg
http://www.ecutune.com/posts/255-2.jpg


I stuck with the pirelli pzero nero m+s because I like them so much on the street. It's definitely not the best tire for the track for the same reason I like them so much on the street. It's the best rain tire I've ever driven on. The huge raingrooves mean that there's a lot less tread and a lot more groove than most tires. Still we've stepped up the width of the tread by an inch and a half with these tires. Multiply that inch and a half by 4 and you have a lot more tread on the ground so it will definitely be a lot better even if we don't get rock solid instant traction with the big shot of nitrous oxide.

Thats awsome, so we can go to a 255 with an 8inch wheel and a 49 offset? Good to know, now lets see thoes time slips:D

You too, where are you at with your Stage II install? Only thing we have left to do to be race ready is the bearings (actually i need to regrease and boot my front axles but I count that as part of the bearing job). The hubs and spindles haven't come yet but Mike sent them a while ago so should be here soon. I'm still hoping to be able to go to the track next wednessday.

Okay, now who's going to do the math - does this mean that 255/35-16 with 50mm offset will fit without rubbing?
-Bill

I need to sell my temporary transport to afford the NOS kit:rolleyes: I wouldn't expect any stage II slips from me untill next summer:( Plus I have to do something about my tranny issue,

I thought I just posted here...where did it go?

I'll post again.

Good luck with the new found traction.

Do you have a photo showing the width of the new tires? I'd like to see what the back of the car looks like.

Ah HA!!! It was a different thread...sneaky guy!

[QUOTE]Originally posted by Earthworm
Ah HA!!! It was a different thread...sneaky guy! [/QUOTE

your quick:D

That's not what my gf tells me. :eek:

The 35 series is only applicable to a 255 on an 18" wheel but lets only worry about width here first. You can go through a simple chart and pick out the appropriate series after you figure out what will fit. The bad news though is you really can't calculate what will fit on the inside side without taking measurements of clearances while the car is sitting on it's tires. The only way you could possibly do that is on an alignment rack.

With a whole bunch of calculation we can glean together some useful information about what will fit though, just but seeing what won't fit on the outside.

I'll do the math though and let you see what I mean.

The width of the wheel is critical.

Factory wheels are 7.5" wide with a +55mm offset. That means the wheel goes back 150mm from the mounting surface and sticks out 40 mm from the mounting surface.

My wheels are 8" wide with a +49mm offset. That means the wheel goes back 150.6mm from the mounting surface and sticks out 52.6mm from the mounting surface. So bascially the wheel sticks inwards the same amount as factory while sticking outward half an inch more. So in this case 74% of the wheel and thus the tire goes to the inside of the mounting surface.

In the case of the factory wheel 79% of the wheel and thus the tire goes to the inside of the mounting surface. So you're putting more rubber to the inside. What can you fit without rubbing on a factory wheel? I don't know. On the smaller diameter wheel you are going to have tire in an area that is tighter to the strut and the shape of the sidewalls will be a lot more bowed on the less wide wheel.

The real problem is in the case of aftermarket wheel. Most aftermarket wheels aren't available in an offset any larger than +42mm. This puts more wheel to the outside. An 8 inch wide wheel +42mm offset would stick out a whole 59.4mm from the mounting surface and a 7.5 inch +42 wheel will stick out 53.7mm from the mounting surface. In the case of the 7.5 inch wheel you're putting 28% of the tire to the outside in the case of the 8" wheel you are putting 29% of the tire to the outside.

So now you could take those percentages...factory 21% outside, 8" +49 26% outside, 7.5 +42 28% outside, 8" +42 29% outside and multiply by the crosssection width of the tire.

If we take my tires at 10.2 inches we see that @21% 2.14", 26% 2.65", 28% 2.856", 29% 2.95" of tire goes to the outside. I can tell you from looking at my car that the 28% and 29% instances will rub on the outside.

How big of a tire you can fit on stock wheels will most likely be determined by inside clearances.

I like your girl but the visual of you is TMI:D

Nice looking wheel and tire combo Michael. I'm sure your traction will be improved greatly and it'll be cool to see what times you put down next week at the track! :)

-Chike

:confused:




















So what are your wheels, where did you get them, and how much did you pay?:D

Hijack! Sorry How hard would it be to make a graph showing wheel/tire sizes=y and offset=x with svx compatibility highlited? Anybody have some spare time and good knowledge of tires? Btw nice setup, what's not the cheapest setup?

I don't know if that would work. What doesn't rub on one SVX may rub on another.