tyoung88

I'm getting some 18" wheels put on tomorrow. They are ALT 5-Spoke "Sonix". After speaking to the dealer today I found out two things that were somewhat questionable.

First the wheels are 18x7.5. I believe the stock 18's that come with the Z are 18x8 so I guess I may need spacers.

Also the dealer said that they would be putting Falken 451 in the same size all around 245/45/18. My current 17s stock wheels are much smaller in front and I beliieve the stock 18s are similar. Does this setup have any major negative impact on performance or driveability?

Thanks so much.

Boomer

All Z 17" wheels/tires are 7.5's fr and 8's rr; the 18's are standard fr and rr on the Touring 6MT and Performance, the Track model has 8"s fr and 8.5"rr. Why are you putting on smaller diameter wheels on the rear than your stock 8"s? You need to hold up and do a search for the humongous tire and wheel thread we have on this site. I can't link you, but the originator is TX STYLE and if you PM him or one of the Moderators in that section you can get info on your swap. I would make some excuse and delay your swap until you can get an answer from one of our more knowledgeable members if you can.

The Z was designed to have a stagger with wheels and/or tires and some of the electronic aids like VDC,LSD, TC and ABS can be screwed up by no stagger. I don't like the sound of it, but I'm not the expert, others here are.

biscotti

Agree with Boomer, tires should be staggered. 245s seem a bit wide for 7.5 inch rim width. I would bail.

Buub

iTrader: (1)

Yeah why go smaller? That makes no sense to me if you're spending good money on new wheels.

The tire needs to stretch a bit. Putting 245's on a 7.5" wheels is not going to give you great traction.

D'oh

A couple things:

1. You should be fine with that setup - I run 18x8x35 wheels with 265/35-18 race tires on all four corners. I went for a 50 mile test drive last weekend and had no issues with VDC/TCS or ABS activating unexpectedly. However, I did not check to see if they were still functional either, but I see no reason why they would not work. No SLIP lights came on or anything like that. Also, you'll notice that the 265 tire is significantly wider than an 8" rim. There is a definite bulge, but they do work.

2. If you can get an 8" or 8.5" wheel, then you should do that. Not only will it fit the 245 tires better, but it will give you room to grow in the future if you want to. I would be very hesitant to buy a 7.5" wheel for the Z since the car is so heavy and can handle so much more tire. If you are uncomfortable using 245/45's all around, you might try looking for a 245/40 in front. This will put the tire stagger very close to the stock 18" tires, and will eliminate the ABS/TCS/VCD concern. Just for reference, I'm running 245/40-18 in front and 245/45-18 in back for my street tires.

Good Luck!!

-D'oh!

chazzg

iTrader: (1)

If you have a Base model without VDC than the Stager won't mater. but dude don't get smaller than 8 to 8.5 in the front and 9 tom 9.5 in the rear. If you do your handling will suffer

Buub

iTrader: (1)

That's not true. Read above. We're also talking about ABS which needs to know relative wheel speeds just as much so it can determine if a wheel is locking up.

ares

iTrader: (2)

same width is fine(245 is fine on a 7.5 as well I think) but same hight isnt a great idea, which will still keep you from rotating.

Id also look for something wider.

IME rims that dont come wider are typicly cheap. if this is for a performance benifit I think this swap is gonna hurt you all around. if its for appearance, well have fun; so long as you accept that its an asthetic mod.

tyoung88

Thanks for saving me guys.

Gonna hold off on the rims. Make the dealer get me stock size setup on rims and tires.

DZeckhausen

The stock 350Z has a tendency toward understeer at the limit of adhesion. This is a function of the factory selection of:

• Swaybars (front & rear)
• Springs (front & rear)
• Shock valving
• Tire sizes (front & rear)
• Tire pressures

This is not an exhaustive list, but it covers many of the bases.

Owners can and do change the handling of the car by modifying any of the above. Unless you go to silly extremes, you will NOT screw up the ABS, the LSD, the VDC, or any other electronic controls!

In general, wider rear tires tend to contribute to understeer. If you change to the same width tires all around, your car's handling will shift somewhat toward the direction of neutral handling. For racing, this is a desirable result and for the purpose of rotating tires, this is also a good thing.

Keep in mind that the factory tire width selection is made with input from Nissan's legal department as well as the Marketing department. Legal wants the car to understeer so they don't become victims of too many lawsuits from owners who lift off the gas in a turn at the limit and swap ends. Marketing wants to increase sales by having "aggressive" wide rear tires which have grown in popularity along with drag racing. Optimizing a car for drag racing does not necessarily optimize it for turning and stopping! The performance purists in Nissan R&D do not get to make the final call on how the car is equipped. So don't assume that the car, as delivered, is optimized for handling and performance.

This is exactly the same discussion that went on in the 2nd year of production of the BMW E36 M3. In 1995, the car came out with the same size wheels and tires all around. The next year they went with a staggered set-up. All the racers ended up buying sets of four rear wheels and using equal width tires at the track.