Hey Everyone,

I'm a n00b when it comes to 350Zs, mods, etc, and I'm brand new here. Good to be here and thanks for your help in advance.

I recently bought a 2004 350Z Performance. It's needing new tires, but the previous owner changed it from stock. Aftermarket rims, type 2 coilovers, and front and rear have a negative camber (rear more than the front).

I visited Discount Tire today (very helpful guys). He took my front and rear wheels off and determined that the aftermarket rims are 9.5" wide front and back. I have no idea what the previous owner was doing (perhaps when he changed his rims he didn't change his tires), but currently the car has 225/45/R18 front and 235/45/R18 rear. Forums were helpful enough that I determined this is way too narrow.

Discount tires is recommending 255/40/R18 for front and 255/45/R18 for rear.

Here's my questions:
1. The obvious: will they rub?
2. If so, can I go down to 255/35s? The gentleman at Discount Tire said 35s would not support the weight of the car.
3. Do you have any other suggestions based on the info I've given?

Thanks - I appreciate it!

Kevin

 

And I'm seeing based on posts that others are running 35s and even 30s. I'm assuming the information Discount Tire gave me is wrong?

 

Stock 18" Tire Sizes
225 45% 18 25.97
245 45% 18 26.68

In keeping with the +/- 10mm (or so) "height rule"....

245 40% 18 25.72 FRONT
255 35% 18 25.03
255 40% 18 26.03 FRONT ALTERNATE
255 45% 18 27.04
265 35% 18 25.30
265 40% 18 26.35
275 35% 18 25.58
275 40% 18 26.66 REAR
285 30% 18 24.73
285 35% 18 25.85
285 40% 18 26.98
295 30% 18 24.97
295 35% 18 26.13
295 40% 18 27.29

From this, no real good 35 series alternative. These are pretty much the "trusted" size choices. You CAN go wider but on 9.5s, not advised.

 

Very helpful, thank you.

 

And, be aware that too large a difference in overall diameter front to rear will not agree with the TCS and/or VDC, if your car has those features. I'm sure someone else with more complete knowledge will chime in.

 

Damn mobile posting... Sorry

 

It does.

Would 245 / 275 be acceptable then?

 

^^^ 245/40-18" front with 275/40-18" rear works perfectly with Nissan's VDC on the 350z Performance model.

 

Well that's my answer. I've verified I have the performance model.

 

Well, I ended up going with the following...

Discount Tire has a tire exclusive to them, which they highly recommended, comparable to the Michelin A/S 3s but with better snow traction.

Continental ControlContact Sport A/S
245/40 R18 - front
255/45 R18 - rear

Unfortunately 275/40 R18s were not available either in this tire or the DWS 06, and I didn't want to pop for the A/S 3s and loose some snow traction. I'm in the Midwest. And, although the 255/45 R18s come in at 27.04 vs the stock 245/45 R18s at 26.68, hopefully they'll work. If not, they said they'll swap them out until I'm happy.

Thanks again, guys.

 

You will like this setup. Your setup 245/40 R18–front and 255/45 R18–rear) reduces under-steer, making your car point more aggressively in, through, and out of turns. You need to be aware that this setup puts you more near over-steer.

I ran 245/40 R18–front and 245/45 R18–rear for awhile, and this setup was a lot of fun.

 

Thanks for that info, Spike. As I said, I'm new to all this modding stuff. Could you go into more detail about why this tire config puts one more near over-steer?

Thanks!

 

The Z in factory form and with it's OEM staggered tires will understeer. As you reduce the difference between the front and rear tire widths, you are shifting the cars tendency from understeering to oversteering. Although if the rear does actually have more camber than the front as you've said, that will reduce the tendency to oversteer (I'm assuming when you said "more camber" you were implying "more negative camber")

 

It's not going to make that much difference, if any, that you'll feel driving on the street. If you want to fine-tune the handling, you can use tire pressure and ant-roll bar adjustments and get consistent results.

 

There are multiple factors affecting the way your car handles. dcains mentions adjusting tire pressure and stabilizing bars.

Tire size also affects handling. If you put wider tires on the rear than the front, and all other things being equal (e.g., suspension, camber, etc.), the car tends to push forward in turns at speed. That is because the wider rear tires can “overpower” the more narrow front tires. Some drivers refer to this as “plowing.”

If the front tires are the same width as the rear tires, and the car has a neutral 50/50 weight distribution, it is possible the rears could release (spinout) in a hard turn at speed.

 

Don't be surprised when you take a turn at speed and your slip light starts flashing and your power gets cut. Mine had stock size with just new tires in the back and half warm in the front and it was unhappy about the difference. But if you dont hit the twisties your probably never going to see it.

 

^^^^^ Totally this.

If you push the car 8/10ths or more, there might be some issues with a changed handling characteristics but this is insignificant enough change not to worry about it.

If the car is pushing, put more air in the front, staggered by about 4psi

Conversely, too much oversteer, stagger by 4psi rearwards. But I really don't think you're going to need to do this, particularly in day to day driving.

This all has to do with slip angles of the tires and a lot will depend on the particular brand/type of tire with sizing being of a lesser contributor towards under/oversteer as well as all of your other suspension components coming into play, e.g., shocks, sway bars, alignment, etc...

IOW, don't stress over this.

 

Ultimately it depends upon grip (front compared to rear):

1. Front grip less than rear: under-steer
2. Front grip greater than rear: over-steer
3. Front and rear grip equal: neutral steer

There are various factors (tire width and tread, camber, suspension setup, etc.) that influence handling.

 

And with the Z , having equal tire width front and rear will bring you closer the neutral, but not enough to make the car oversteer.

Throttle induced oversteer will be easier with less stagger

 

^^ I really liked my 245 front and rear setup for handling.

I recently mounted new wheels, and stayed with a staggered setup (245 f with 275 r).

I want to try an all-square-width setup, mounting 275 all around. I will need to swap out my front wheels.