different width tires on same size rim

So I've got 13" x 7" wheels and a car with a roughly 66/33 rear/front weight distribution. I think that it'd be a good idea to put more rubber in the back. I'm looking at used race tires to run in autocross and am wondering what the peanut gallery thinks about running 7" wide in the front and 8" in the back, or similar ratio. I've been told that a wide rim/narrow tire will make for stiffer sidewalls, but......

I asked this a while ago and the general consensus was within the recommended rim width range you wont notice any handling difference.

I'm pretty sure with that kind of weight distribution you are just screwed

Only thing that could possibly be good for is a drag car. What kind of idiot builds something like that then tries to make it turn ?

Will 13" rims clear the brakes?

It would be interesting to give it a try. The front wheel drive autox crowd does vary front to rear tire widths for the same reason (nose heavy weight distribution of course). It does seem that they have the most success when they vary the rim width by around 1/2" while adjusting the tire width accordingly. I was kicking around trying it on the rabbit diamonds and running a 235/225 setup.

Aren't there a million different setups available for the vette between the camaros and different iterations of corvettes. It would seem a significant change in swaybar rates might also be in order. How different is the weight distribution from the untrimmed factory beast?

Confused on the vette comment, I'm not sure how that's relevant

Hah my mistake on the vette comment..

icaneat50eggs wrote: I'm pretty sure with that kind of weight distribution you are just screwed Only thing that could possibly be good for is a drag car. What kind of idiot builds something like that then tries to make it turn ?

Beats me. but then there's always a knucklehead willing to take a project like that off your hands.

Porsche uses larger tires in back regularly. The obvious thing is to simply buy different size rims. I'm just trying to keep costs down, and was interested in what the hive mind thought on the matter.

You'll get very little increased tread on the ground by jamming an 8" wide tire on a 7" wide rim. Much of the tread will be catching air at the sides of the tires like this:

Also you will indeed get an effect that feels like softer sidewalls.

I wouldnt go larger than the width of your rim for the reason that your sidewalls will feel softer. If anything go slightly smaller, not a lot, but some. Ive found that it helps alot on my friends autocross cars.

in the past … stock class a-x'ers have found that Hoosiers can stand being pinched (275 and bigger on stock 6 1/2" rims) but that street tires don't do so well when pinched

I'd run square at first, then get a pair of bigger rear wheels if you feel you need it.

^This. Staggered tire setups are much more expensive to run than square setups. If you need more grip on one end, it probably won't hurt on the other end - and even if it does, you might be better off adjusting something to compensate and sticking with a square setup.

I run in the VW/Porsche circles and very often these cars will have bigger/wider tires in the rear than the front due to the weight difference front and rear.

If you go to an auto-X and find any VW based Dune Buggies running the course, they ALWAYS have increased sized tires in the rear, most often on the same sized alloys. The weight in the rear usually flattens the wider tire to make full contact with the track/road. Never seen a rear engined VW or Porsche with the tread patch rolled up in the rear.

With the engine and transaxle weight a larger rear tire is a big plus. Street or otherwise.

I read an article years ago about the HKS Evo out at Tsukuba or however that's spelled out of SCC mag. Had an interesting thing about the tire setup, where they were running an oversquare tire set. Same size tires on all 4 corners, and narrower wheels in the back. What it did was give them a very square tread pattern and maximum bite on the turn in- with less of a progressive breakaway, which is what you want on the front, especially in AWD. Made for killer initial bite. The back wheels were actually narrower, and it gave them a slightly bubbled tread pattern in the rear- not as much lateral bite on the initial turn in (but the front is doing that work) but a much more progressive breakaway, and the ability for a much higher slip angle before it becomes uncontrollable, while allowing the front end to remain planted. That's always really stuck with me. I tried something like that a couple tire sets ago on my ms3 and it was very interesting. IF you've never driven one, they have spooky snap oversteer. Because the shocks and springs are a bit understiff for the brakes and power of the car, it tends to unload under braking. Load up the front end, turn in, and the ass will unload and actually hop over. It's kinda scary. First time it did it to me I thought for sure I was going into the cabbage. Because the tires were square, there was no breakaway warning- it just happened. With a fatter tire on the same rim, the breakaway was a lot more progressive and allowed me to catch it a lot easier. YMMV and all that, but that's what I know of the story.

Hopefully, you can find a pair of 13x8 wheels for the rear.