I recently purchased a new set of tires for my stock 17" rims. I picked up a set of KDW g-force sport that was not in the perfect size (245-45-17). I get the occasional slip light, which I understand why that happens. I know I should have picked different tires sizes, but at the time I got the flat that was all the shop had available. I am dealing with the slip light coming on since the wheel rpms are not the same. The thing that is really bothering me is that these tires have a stronger sidewall than the stock potenzas, and supposedly better grip, but it feels like my car can't handle turns like it used to. I feel like I have lost a bit of handling even though the tires are wider and also stronger sidewalled. I know it may sound stupid, but I am actually very sure of the results. I was wondering if anyone knows something I may have overlooked that can be contributing to this. Thanks and sorry so long.

Alex

 

You should have had the shop plug it, then get the right size tires at another shop.

Your rear tires are a smaller diameter than your fronts, if your fronts are stock sizes. Not much good can come from having smaller diameter rears than fronts. Your rear probably sticks better than your fronts now and it's the front end that feels icky.

The geometrey is all out of whack.

 

Thanks Chad. I wish I could have just done that, but the shop said they were not repairable. Which I can see why if they wanted to make a quick sale. I totally forgot that the geometry of the car is thrown off now. I thought it would just affect the tcs. In anycase would that attribute to feeling really squirely on turns and feeling less stable at higher speeds while turning too? Or just the rear end sticking too much?

 

Yea, it just seems like your car is gonna really want to understeer now, if the rear sticks that much more. You could just order a set of 245/45/17 for the fronts, and just drive around with the TCS off, or the VDC off, whichever you have!

 

Alex,

I've "been there" and understand your concerns. The Z is fun to drive, and the wrong tires can ruin the experience. I would replace the tires so you get back to enjoying the ride. After all, that is why you bought a Z. Tires are not that expensive; and what the heck, they wear fast anyway.

--Spike

 

You drive an Enthusiast with TCS. I am 99 percent certain that TCS is not effected by tire size.

 

OP. When you say new set, did you get a complete set of four tires or just a matching pair for the front or back?

 

This is a good point in itself. TCS only measures the differences in the rear wheels. The VDC will affect all four tires.

 

New tires are slippery. All new tires. Put 100 miles on the tires, then review handling.

 

the tires have been driven for well over 600 miles. I only bought the pair for the rear sorry for not clarifying earlier. Davidv was corrected in stating I have an enthusiast with TCS only.

 

why not match up the front with 235/45/17 since you went OE+1 on the rear?

 

I didnt initially do this because the fronts had plently of life in them. I bought the car used with 2000 miles on it. I replaced the rears because they were already pretty bald before the flat. My fronts still have quite a bit of life to them so I didnt want to throw those away seieng as how tires are expensive. Also my stock tire size was 235/50/17 so i know the tires diameter is smaller in the rear.

 

Your rear tires are wider and probably made from a stickier compound than the fronts which will contribute to increased understeer compared to your stock setup. The difference in overall tire design including the tread pattern will also be a contributing factor. Who knows what will happen when you hit some wet weather?

I've seen posts like this a few times on the forum and the solution is always to have a matched set of 4 tires. Since the rears are newer and nicer, I'd recommend a set of 235/45-17 in the front. $300 is a small price to pay for peace of mind and the enjoyment of a sports car. When you think about it tires are the most important part on the car and the absolute last place to skimp on since they are the only part of the vehicle that touches the road. This will also fix your extra sensitive TCS issue.

 

^You are absolutly right. I think that I might just go ahead and do this. The only thing I wanted to mention to you also is that when I do take turns, I dont feel as though the car will understerr rather, I feel like I am getting more body roll, and perhaps my back end will come loose. The reason its driving me nuts is the tires I purchased are known to be better than the stockers. Maybe you are right, and I just think the rear will come loose, and in reality im getting understeer. It's just that since past experiance with understeer in other cars, it was never really the same. Thanks for the input.