255's or 245's?
 

I just ordered some T1R's from Schwab's and right now I have 255's on the rear. When I first got my TSW 18's we started with 245's in the Proxes 4. After the rears had to be replaces, we went with 255's and I love how they fill up the wheel wells, but they feel a little squirly in the rear. Not like I'm not getting traction, but like the sidewall has more flex to it.

Is it better to have the tires stretched a little for cornering, but lose a little of the contact patch, or is it better to have a little wider contact patch, but feel the back want to wander a little? I've actually lost a little confidence in my cornering, but this may all be in my head.

Anyone else have any experience with this?

Its best to select a tire size recommended by the tire manufacture for a particular wheel. Plus or minus 10 mm will make little if any difference

Thanks. I didn't even think about looking at the TSW website. They're recommending the 225, 235, or 245's, but that doesn't really make much sense since the 245's were so stretched. At any rate, I'm noticing a huge difference in the character of the car with just that little bit of difference. Think I'll go back to the 245's.

Wheel size , apsect ratio and quality of tire make a huge difference . Please post the rest of the info.

Not sure if I’m answering your question, but there is a big difference in the “feel” among different tires when the sidewall flex varies significantly. It (sidewall flex) is more noticeable with profile (height) than width. To get the best and safest handling, you should run the tires at the psi Nissan recommends, which is 34-36 psi. That gives you the best tire contact (i.e., “grip”) with the Z’s weight and handling characteristics. You shouldn’t overinflate the tires to get a stiffer feel. Doing that is certainly a temptation when you first start running a tire with a softer sidewall, but overinflating tires reduces contact and provides less grip when cornering hard.

I’m currently running Goodyear Eagle F1 GS-D3 tires (F-245/40-18"and R-245/45-18"). The Eagles have a softer sidewall than the OEM Bridgestones Potenza RE040 tires, and the Eagles initially felt “wiggly.” After just a few hours of driving on these new tires, I became very comfortable with the different handling characteristics.

Hoping I didn’t misunderstand the question and that this information is useful.

--Spike

^Good info there.

Side question...Spike, I'm looking into getting those tires next summer. My rear stock tires are wearing low (not at the indicator yet) with almost 20k on the clock. Is it going to make a big difference if I leave the stock tires on the front, and replace the rear ones with the GS-D3's? Also, how is the fitment with the different size on the front? This is assuming you are still on stock wheels.

Thanks!

^^ I experienced the “feathering” problem with my fronts and Nissan kindly replaced these with new OEM Bridgestones Potenza RE040. When I replaced the rears with Goodyear Eagle F1 GS-D3 245/45-18", I was still running the OEM Bridgestones on the front. Although the sidewall characteristics are quite different between the rear Eagles (soft sidewalls) and the front Bridgestones (stiff sidewalls), I did not have any difficulty running these different tires front to rear. The Z’s great suspension and geometry allow this seemingly incongruous tire setup. The car drove just fine with this tire arrangement.

I did replace the fronts with Goodyear Eagle F1 GS-D3 tires (245/40-18"). I like this setup better. It provides more neutral steering, and it feels better with the same sidewall flex front to rear. Fitment is very good, front and rear (I have a Performance model with the OEM 18x8” wheels).

I’ve had the opportunity to drive Z’s with various tires, and I really like the Goodyear Eagle F1 GS-D3 tires. They have a softer sidewall making the Z’s ride more comfortable, stick like glue to dry roadways, and adhere exceptionally well when it’s wet. The only tire I liked better was Michelin’s PS/2.

--Spike

Ruining, were your tires properly inflated and did you have a good alignment?

also, what rim size do you have? 8.5 or 9/9.5?

if your sidewalls are ballooned out it can cause that floaty feeling you are talking about, and the T1Rs are supposed to have a fairly soft sidewall from what I have heard.

I have 255s on my 19x8.5 fronts and they look and feel fine. 275s on the 10.5 rear

Thanks for the replies. I've got 8.5 front and 9 rear. I'll be going with the 245's and see how it goes. I won't be doing much aggressive driving through this fall/winter, so it'll give me plenty of time to do more research on which tires.

Yeah, motor, they were properly inflated. The only difference was going from 245/40/18 to 255/45/18. I'm going back to the 245/40/18 and go from there.

And spike, thanks for the info, man.