95jersey

I may have asked this before, but looking to order some new tires and want to cure a slight understeer problem at the same time. I run 275's in the front and 315's in the rear and no matter what sway bar I use, the 275's just don't want to hold at speed compared to the 315's.

I run Kuhmo V710's and unfortunately, they don't make a 285. So, I would have to go 295. Without having to buy 2 new rims, does anyone run a 295 on a 9.5" rim (stock Z06 front wheel)? I would think this is pushing a 9.5" rim to it's limit. I just don't want to be doing 140mph at Pocono and have problems.

The 275 fits perfect, so I am thinking a 295 isn't that much wider at actual mounting point.

Any comments?

VetteDrmr

Can't speak to Pocono, but I'm running 275/305 RA-1s on stock wagon wheels (the relevance being the 18x9.5 rear wheels). That's +40mm front and +30mm rear over stock sizes.

So, I think you'd be OK.

HTH, and have a good one,
Mike

AUTO_X_AL

That is the preferred setup for SCCA SS cars. 295F and 315R. You will be in great shape with those. We run 295 Hoosier wets on 9.5 and they work great for us.

95jersey

Thanks!

love this place

XPC5R

Watch out, the Kumho 295/17 is a very tall tire, check the specs to be sure. It is not comparable to the Hoosier 295/17, which many ran, that is the same height as the 275/40/17 tires.

Rx7klr can chime in, he's run them on his C4 and I think chose other options.

RX7 KLR

Yeah it is a 295-40-17 VS the Hoosier at 295-35-17.


The 295 Kumho did not turn in as good as the 275, way to much sidewall.

For the most part push is driver induced, to fast on corner entry. Once you have that fixed there are things you can do even in SCCA stock class that will make a C4 into a drift king even with a 275 front and 315 rear.

So before you go and buy some tires try the cheap stuff like alignment. More front -camber, less rear -camber. More front toe out, less rear toe in.

95jersey

I run the Kuhmo 275's now, which are also 40 series, so while I hear you on the 35 series Hoosiers, I already run the taller tire today anyway. So, I am not loosing anything here. I like the Hoosiers, but the cost is higher and I always get less wear out of them compared to the Kuhmo's. So, for track days, I will deal with the higher sidewall to save some money.

As far as allignment, the car runs an aggressive track allignment (-2.5f, -1.5r, slight toe out front, slight toe in rear). I am sure it could be set up a little better, but again it's track days. I have to buy new tires anyway, so I need to spend the money anyway. The cost for the 295's is actually $1 cheaper than the 275's (go figure).

I run fat sways already, so I figure the 295 should help a little with regard to understeer. If not, I saved a $1.

I just wanted to see if there were any issues running them on a 9.5" rim.

69autoXr

The 295/40 is taller than the 275/40. 26.1" vs 25.4"

RX7 KLR

So now we can get into aspect ratios.... The tire has a given width, the height of the sidewall is a % of that width. So in this case you have a 275 and 295, both of which have sidewall that is 40% as tall as the tire is wide. So now do you understand why the 295 is taller than the 275?

275-40 = 110mm sidewall
295-40 = 118mm
295-35 = 103.25mm

Keep in mind these are approximate and will vary by manufacture and will be effected by the size wheel you squeeze it on.

The next thing is the weight. The 295 V710 weighs as much as a 315. That weight is on the outside of the wheel, which is the worst place to have it.

The first thing I would do is go to zero rear toe. When we ran the Victoracer and Hoosier A3S03 we ran a 1/4" total toe in on the rear of our C4. The V710 had so much rear bite we had to go to zero rear toe. The other thing you can do is raise the rear of you car, as little as a 1/4" of rake can make a difference. If have no idea if you are setting this up for a certain class or just to play. Other things you can do, lower the front or a 26mm rear bar.