245's are not designed to be on 7" wide wheels. Its the opposite of "stretched" tires, but both scenarios risk popping a bead. Even more so, if a bead pops in a corner you could possibly flip the car.

So for saftey reasons, I can't recommend it.

Yeah trying to stay in C-Stock. Already got the camber bolts, gonna do the sway later on..wanna feel the OEM one out for a bit first to see how thick i wanna go.

:cheers:

That's the kinda intel i was looking for. I figured something had to be sketchy about that fitment.

Thanks for that info.

I ran the whole 2014 season with SFR SCCA and multiple AAS events in the Bay Area on 245s. I also went to the Crows Landing Pro and Tour. Most of these events were with two drivers (I had a third person drive my car at a few local events too since they needed a car to drive). I also drove to events with the tires on the car. I had zero issues, and neither did the others around me that had 245s as well. I understand what you're saying, and you could be right. However, by that logic you shouldn't attempt 235s as well, right?

I got gashed for saying this in another thread but yes, bead separation is a safety/rollover issue. As long as you keep tire pressures up it won't be a problem. If you start running drag race tire pressures because "more contact patch yo" then you're asking for problems.

Good to know.

Some racers have made a good argument that 225's may be better than 235's for the stock class (including Andy Hollis, multiple times National AX champion). The reasoning is the narrow tires will distribute the weight less, warm the tires faster and have more psi/sq ft to grip the track. I ran 235 Dunlops on stock wheels and did find I slid around alot more than I do now in STX with 9-inch wheels and 245's. Also the tire sidewalls should be fairly perpendicular to the tread when mounted on the rim. Otherwise you will get too much sidewall flex giving you that numb turn in feel.

Andy Hollis does indeed have some data to back that up, but all his testing happens on lightweight FWD cars with proper spring rates, proper camber, and 15" wheels. How much of that is going to transfer over to our 2700lbs FR car with stock springs, no camber, and 17" wheels?

To take this to an extreme, what works for your Yugo may not work for my Porsche.

IMO you're not giving up a ton by going with a 225 instead of a 245. That said I'm pretty sure everyone who beat me at nats had more tire than me.

I am new to autoX having only done it once. I thought it was cool and want to do it just for fun about once a month in the summer. I would like to buy some summer tires for my car and don't really want to mount and unmount tires for the winter. So I was thinking I should get some new lightweight rims and summer tires and just put the stock rims and tires back on in the fall.

I'm glad I read this thread because I didn't realize the restrictions on wheel size for autoX. duh.

I was going to do 17x8 235/40.....but I guess I can't do that now. So you guys suggest 225/45 or 40 for me on 7inch?

Ill have to research crash bolts, camber etc as well

If you are not trying to be competitive and win a trophy, worry less about fitting into a specific autox class and worry more about what you want to do with the car in general.

In other words, If you go with the wider wheels its perfectly OK for autox you just won't be in the "stock" class anymore. I ran in the modified class for years with my last car due to an engine swap and wasn't competitive at all but I was doing it for fun and learning not for a trophy.

Feel free to do what you want to do, then figure out what class you are in later.

I did the same thing as the previous poster when I first started autoX. My car hobby at the time was modding the car for the material high - installing the piece yourself and feeling the difference.

Then when I went to my first autoX, no videos, reading or anything..just heard about it and showed up late (wtf is a course walk and novice meeting? ;p) I didn't know about classes or the cones or anything. It was actually pretty funny as I just destroyed the entire course my first run and was immediately required to have an instructor.

...anyway, my mods put me into STX so I wasn't competitive at all....but the nice thing is you can run in time only which allows you more freedom in your work and run groups.

As a new person, If I were you, I'd just stick to OEM specs and not mod anything unless u got cash to dump. The only "mod" I'd do is have a separate set of wheels/tires (OEM specs) for autoX and daily driving.

Btw, anyone want to buy my 245/40/17 ZIIs and or rims? The tires are in really good condition and just have 500 miles of dd break in driving and a few autoX runs. They're cleaned, and have been stored appropriately in air tight industrial trash bags indoors for about a month now. The tires were driven on my genesis coupe.