I am running no spacers at all. Stock suspension and wheels. I will have to say my turn in sucks now. It feels like im ridding on jello. The overall grip is better but you just have to get used to the new feeling. After my engine build I will be buying wider wheels so I can live with it for now.

 

Hmmm.....that's disturbing to hear. And yet some of the guys who track their cars use similar "oversized" tires on stock rims.

 

You may want to try getting springs and sways. That would help you get that crisp handling feeling back.

 

The over-sized tires look retarded..

..more harm than good..

 

But not with that much sidewall. A wider 285/30/18 has 3.3" of sidewall, while the 275/40/18 has 4.3" of sidewall - yikes! The 275/40 has a HUGE sidewall. He is feeling all the squirm because there isn't enough wheel width to handle all that sidewall. For street applications, a 275 on a 9" wheels is pushing it, a 275 on a 8.5" wheels is just too much, hence what he is experiencing. The 245 on the 8" isn't as bad.

The tires don't look as bulged as I thought they would, but the Kumho MX = pooh, IMO and experience. Part of the horrible turn-in may be b/c of that Kumho, and the balance because of the oversized tires.

 

They are most likely using different tire compounds with much stiffer sidewalls.

 

A 265/40 on the rear would probably get rid of or help that jello feeling.

Since the 275 rears are bulged a bit, you're not really getting anymore traction with a 275 vs a 265 (unless you are airing way down for drags) but the 275 is giving you a slightly taller sidewall than the 265 would.

I was thinking of going with a 245/40 and 265/40 setup on my stock '08 wheels but decided to just get aftermarket wheels sooner.

You might have some luck improvong the handeling if you play around with PSI settings and see what helps the most.

 

Most of the time thats for Autocross, much lower speeds.

 

You'd also have ~1/2" less tire width, and a more appropriately sized tire for an 8.5" wheel. 245/265 on stock 18s would be a nice combination, and about the max I'd go for the street.

 

OK, sorry to be the village idiot again, but which would be the better size for the rear - 265/40/18 or 265/35/18? (yes, I checked the size diameter calculator already).
BTW, I'm trying to put together a car for track use only (road, not autocross or drag), but hoping to save some money by using my stock wheels.
Thanks!

 

Remind us (or at least me) the size (all 18x8.5?) of all 4 of the wheels you plan to use. . .
If you use your stock wheels, what would you drive on daily? Or would you get a tire that can sort of do both (that gets costly if you drive many road events). You can buy aftermarket wheels for pretty cheap (shameless plug: like the set of 5Zigens GN Pros I have for sale with RA1 tires on them ).

 

The stock wheels are 8" front and 8.5" rear (they came off my 07 roadster). The car I just got is an 03 coupe which will be track use ONLY (apart from the 4 hour drive to the track - I just don't want to get into the whole trailer thing at this point).

 

By a set of 17's. But if you must save some cash , just buy a set of cheap 9.5's for the rear and run your 8.5's up front. What tires are you looking at ? Street, R comp or slicks?

 

If you are really going to use is at a dedicated track car, you need to consider spending a few hundred bucks for wheels. Most trackers like to run a square set-up, which gives the added benefit of rotatability. Others run 245/255 FR and 275 RR, which can not be done on stockers IMO.

I like 17s for track-use because the wheel purchase and tires are cheaper. One can often times find 17x9 Koseis or 5Zigens on clearance for super cheap, and used wheels are abundant on the classifieds forum. You don't need to trailer it.

If you are dead-set on running the 8/8.5" stockers, which I think you'll quickly outgrow and dislike, I'd suggest a 245FR/265RR.

 

Which brings me back to my original question - 265/40/18 or 265/35/18 ?

(Meantime, I really do appreciate all the other info; I was hoping to avoid it, but I can see another wheel purchase sometime in the future!!!!!!)

 

IMO, neither: 255/40/18 Falken Azenis RT615s. They run a lil' wide, so you actually get slightly more than your typical 255. I've used these on 8" wheels before without squirm. Just watch your tire pressures - keep them less than 39psi.

 

Thanks buddy