bobstaff147

I've got several questions about tires and wheels on a touring 350z MT with stock 18" wheels.

I've just noticed that my original rear tires are worn out after 18000 miles (the fronts were replaced by Nissan 4000 miles ago and so are fine), my first question is this a reasonable milage for the original rear tires? I do drive quite fast but do not feel I've been very aggressive, so I was expecting more miles.

This got me looking at tires, I've always liked goodyear tires so after reading a few threads that were mostly favorable I picked the Eagle F1 tires. Then just for fun I checked how much it would cost to get a full set even though the fronts are still ok. I found Goodyear do not make a 225/45 R18 which is the size of the original front tires.

Now to the main part of my question, I know you can put different width tires on rims so maybe I could find a goodyear that will fit the front. What are the pros/cons of this? Is it better to go a little wider or a little narrower?

Beyond putting a different size tire on the same rim I can put different rims on which leads to the following questions.

1. What size rims/tires can be made to fit on a 350z without having to modify any bodywork.
2. What are the pros/cons of larger/smaller wheels larger/smaller tire sidwall in terms of performance for road driving.
3. What is necessary to keep the tire pressure sensors on new wheels.
4. How do different wheels/tires effect the brakes (if at all), would the brakes need modification either to make them fit or to compensate for differences in performance.

I'm not so much looking for recommendations of which wheels/tires other people are using or like/dislike. I'd like to understand more of the theory so I make my own informed decision.

I'm sure this is all obvious to many of you, if so sorry, I've searched the threads and google and not found a good source of information.

Thanks

Kolia

iTrader: (2)

www.tirerack.com will answer all your questions.

-EL

Well Bobstaff, Kolia is correct in saying that ALL the information you're asking for can be found on TireRack.com and they are nice people to deal with, good pricing too. But, that doesn't really answer your question, so here is my attempt. I just went through this same saga recently so I feel your pain, and it's fresh in my mind. Your first question is the hardest to answer, but I'll give it a shot.

1. You can definitely fit a 265 width tire in the front and a 285 tire in the rear. A 275 front and 295 rear might fit, but these are tight. Once you've decided what tire width to run, you just need to find a wheel to fit it. A 9.5 inch wheel can fit in the front and a 10.5 inch wheel can fit in the back. Most tires will fit a range of wheel sizes, for instance most 265 tires will fit a 9-10.5 inch wheel width. Do a web search for "Tire size calculator" to learn how these relationships work.

Offset is important here - offset is a measure of how far away the wheel sits from the car. Too little offset and the wheel/tire will rub your suspension. Too much and you'll rub your fendors. Generally speaking less offset will give you the "Big Lip" look, which some people (including myself) like. Also, you want to keep the offset as close to stock as possible in the front end especially, because changing your offset changes your scrub radius, which will cause handling problems. To learn more about the theory here, do a web search for "wheel offset" and "scrub radius".

2. Wheel radius is, like many things, a tradeoff. Smaller sidewalls are generally stiffer and more responsive, but bigger wheels weigh a lot, increasing unsprung weight and pushing the weight out closer to the edge of the wheel/tire, increasing rotational inertia that the engine has to overcome to accelerate. So for acceleration, the lightest and smallest wheel is best (lowest rotational inertia). For handling, the lightest, biggest wheel is the best (to get a smaller, stiffer sidewall). That said, bigger wheels made of the same materials with the same construction methods are always going to weigh more, so for performance you're generally best off going with the smallest wheel that will fit the tires you want to run and also clear your brakes. So, for the Z in particular, 17s if you run small brakes, 18s if you have or want to run big brakes. 19s and above are all looks.

3. See this thread for pressure sensor info : https://my350z.com/forum/brakes-and-suspension-diy/186197-how-to-make-your-own-aps-tire-bands.html

4. Wider tires = more traction = faster braking. Aside from that, larger than stock tire diameters will put more stress on your brakes, and the higher rotational inertia of bigger, heavier wheels mean the brakes will have to work harder to slow the wheels/tires down. The only other issue to worry about is making sure the wheels you pick will clear your brake calipers.

Some other things to consider: From the factory the Z has a staggered setup, with wider rear tires than fronts (10mm wider rears). The stock Z also understeers somewhat (at least, mine did). If you increase the stagger, you'll also increase the understeer. There are ways to counter this with aftermarket suspensions, but if you have a mostly stock car, you might consider eliminating the stagger and running the same width tires all the way around. At the very least, I wouldn't increase it.

Also, the tires in the front and rear of the Z are slightly different diameters, and the VDC (if you have this feature) uses the difference in tire diameters to help in its calculations. Varying your tire diameters from stock can/will play havoc with the VDC so you may have to disable the VDC if you vary things too much from stock diameters.

And, I know you didn't want specific setups, but I run 265/40/R18 tires mounted on 18x9 wheels with a +25 offset, all the way around. I don't have VDC, so no problems with that.

Good Luck!

davidv

iTrader: (2)

Tire width: I recommend OEM width plus or minus 20mm.