Folks, I've read threads on this topic for a long time on this and other boards, but have not yet been convinced of the truth. I want to use 255/40 rubber on 8.5x18 wheels on all four corners of my daily driver, this to balance the handling, reduce tire wear/feathering, and keep the wheel/tire size more appropriate to the power level of the car. I have an Enthusiast, so no VDC but it does have TCS.

My question is: will the TCS or braking be negatively effected because there would be no rpm differential between front and back wheels? If not then I'll probably go with the setup mentioned. If yes, then I'll go to either 245/40s or 255/35s on the front and give up the ability to rotate front-to-back. Who has done a non-staggered setup without VCS and lived to tell about it? Thanks for your help!

 

My guess is "YES". The purpose of TCS is to reduce wheel spin of the drive wheels. The only way it can determine that is if the rear wheels are spinning at a different rate than the front ones. Since it is preprogrammed with a certain stagger, then if you do away with the stagger, both the front and rear wheels will turn at the same rate. TCS will see that as a sign that the rear wheels are slipping and kick in. You may have to drive with TCS turned off all the time.

 

I feel that it will not require the driver to turn the TCS off entirely. How many aftermarket wheels of varying sizes do we have in the Z community? Tons. I think a far greater impact would come from a VDC and BBK combination.

 

isn't the stagger in the wheels in width not diameter? Therefore, the wheels would be rotating at the same pace regardless of how skinny or wide you went on the tires.

 

Yes, however different contact surface permits the wheels to release/increase traction sooner/later than the computer is mapped to correct.

 

No. The computer looks at the rotational speed of all four wheels. Because the back tires are "taller" they have a larger OD therefore they rotate at a slower rate than the fronts.

If you put the same size tire or same height tires on all four corners, the front and rear wheels will rotate at the same rate. The computer already thinks that the rear should be rotating at a slower rate. If it sees that they are rotating faster than expected, it will assume that they are slipping. That causes TCS to kick in.

Here is how Nissan explains TCS in the Factory Service Manual....
TCS Function

The wheel spin occurrence of the drive wheels is detected by the ABS actuator and electric unit (control unit) using the wheel speed signals from all four wheels, so when wheel spin occurs, the amount of wheel spin is reduced by controlling the hydraulic brakes on the right and left rear wheels, cutting the fuel to the engine, and partially closing the throttle valve to reduce the engine torque. The throttle opening is also controlled to obtain the optimum engine torque.

Depending on road circumstances, the driver may have a sluggish feel. This is normal, because the optimum traction has the highest priority under TCS operation.

TCS may be activated any time the vehicle suddenly accelerates, suddenly downshifts, or is driven on a road with a varying surface friction coefficient.

During TCS operation, it informs a driver of system operation by flashing SLIP indicator lamp.

 

its doable, i dont have a staggered setup right now, and the TCS doesnt kick in very often, unless im going around a sharp turn and it starts slipping out. so theres the answer to your question

 

I run 275/35/18 front and rear for track. TCS warning comes on with the slightest of turns and I get the lurch lurch. This is usually when coming from or going to the track, of course TCS is off on the track.

When I was running 275/40/18 with street tires I also got the TCS lurch on the slightest application of throttle off a turn. I had to leave the TCS off.

 

This is really strange because it is all new to me. I've been following the Z since July 2002. And none of the threads about wheel offset mention this.

In other words, if I were getting aftermarket wheels there would be no reason to get anything more than the BASE model. Unless you wanted HID headlights?

How about the NISMO LMGT4 18's? How about the 19's?

 

I’m 90 percent certain that TCS will not object to the same wheels and tires all around. If TCS does throw a fit, then I’d chalk it up to the other 10 percent.

 

BTW does the G35 come standard with the same size wheels and tires all around?

 

Yes and no.

The G35 sedan comes with all 4 tires the same size.

The G35 coupe has bigger rear tires.

BUT...

The rear tires on a G35 coupe are the same diameter as the front tires, because they have a lower aspect ratio, so they spin at the same rate.

For instance, a 245/45-18 and a 275/40-18 both have about the same diameter. So even though the rear tire is wider, the diameter is the same as the front, and they roll at the same rpm.

So, the VDC on the G35 expects all tires to roll at the same rate, or it thinks it's slipping.

 

Or cruise control, or any of the other features that the higher trims come with.

The standard tire recommendation for the NISMO wheels are:

245/40/18 & 275/40/18

245/35/19 & 275/35/19

Those are designed with enough stagger so that VDC and TCS will continue to function normally.

 

Thanks. So obviously VDC for the G35 is set-up different than VDC for the 350Z? I learn something new everyday here.

 

to the OP, davesz#3, clayton, and jimster are correct
"will the TCS or braking be negatively effected because there would be no rpm differential between front and back wheels?" - YES

other posts - wow, the misinformation!
"a far greater impact would come from a VDC and BBK combination" - NO

"isn't the stagger in the wheels in width not diameter?" - YES AND NO, YES there is width stagger, but NO it has nothing to do with TCS/VDC. The rolling circumference (ie. wheel speed) is the stagger TCS/VDC is sensitive to.

"different contact surface...the computer is mapped to correct" - NO

"I've been following the Z since July 2002. And none of the threads about wheel offset mention this" - NO, who said anything about offset?

"How about the NISMO LMGT4 18's? How about the 19's" - what is your question? - if you run these wheels OR ANY other wheels with the proper tire sizes then you can keep your electronics happy.

"I’m 90 percent certain that TCS will not object " - NO, as mentioned by jimster and clayton who run that setup; or maybe they're that 10%

new information
"the VDC on the G35 expects all tires to roll at the same rate" - INTERESTING, anybody up for a G35C VDC hack conversion for the 350z?

pp

 

After several days of comments on two boards, it appears that there is no definative answer to my question.

* Some owners report running non-staggered setups without problems
* Some owners report TCS issues with non-staggered setups occasionally.
* Some owners report TCS issues with non-staggered setups all the time

Few have reported if their TCS is kept on or off - that would solve the problem, and this explains why those who track the non-stagger setup seldom report problems. If the TCS is turned off no wonder there is no issue.

One parameter we have not addressed are the years involved. Perhaps some years have different software and will allow different or non-staggered setups. It is no surprise that reverse stagger - smaller rear diameters - causes problems.

In the end I'm getting four 18x8.5s, and PS2s with 245/40 up front and 255/40 in back. This is better balanced than the 245/275 stagger so many use, looks fine, gives a big increase in grip and response over the factory 17s, and I saved a total of 14.6 pounds in wheels and tires. That should offset the increased moment of inertia with the 18s, and maybe even give a tiny boost to acceleration. Thanks everyone for their input in this thread, maybe some day we'll find out the whole story.

 

^^^Why not choose 235/40front and 255/40back? The stagger would still be in the 0.5 - 0.75 range and vdc-tcs should be happy...

I had used front tire with new rear one (stock sizes) and vdc-tcs issues. Even with tcs off, abs would kick in while braking at high speed!

Sorry to give you the advice for a staggered set up. Correct understeer with swaybars and reduce speed before entering corners.

 

Your advice is welcome, albeit too late. The reason for 245s up front? Increased grip over 235s - no sway bar can compensate for inadequate tire sizes. Why screw with sway bars when tires alone can fix at least part of the problem? This isn't a track car - I have other vehicles for that - and the current suspension is plenty for my use. And you can be certain that I'll slow down enough before entering the turns....in my youth I got an adequate number of "Daytona stripes" on the sides of my cars....

 

allthough i can not currently contribute much to this thread, after christmas i will be running 255/35/18 all the way around on touring 18's. i will post TCS experiences and differences from the enth 17's after driving a few days. frankly, i'm not too concerned since i NEVER use the TCS in this vehicle. hitting the TCS button is second nature to me now.

 

This is the real worry for me, I can live with the TCS issue, but if the brakes go goofy you could die on these Houston roads!