hmm not sure if this will do anything but hey it always worth a try. Try reseting the ecu?

 

Not sure if these were the correct wheels to be on this car. Would that make a difference? Is the computer set up based on certain wheel diameters? As far as the 255's on the rear go, I just took off some 235's. It was doing the same thing with the 235's on the rear. Also was doing the same with a 245/45 on the rear. The 235 and 245 are within the 3% that is supposed to be happy with VDC. But my little Z is NOT happy.

 

And how do we reset the ECU??

 

Agree. Difference in circumference is 4.5 percent. This may be too much for VDC.

 

You have too much overall diameter difference between your fronts (225/50-17”) and rears (255/50-17”) tires, and its messing with your VDC-equipped car.

A couple of ways to fix this:

1. Keep your 255/50-17” rears, and replace your front 225/50-17” fronts with 225/55-17” tires.
   
2. Keep your 225/50-17” fronts (they are the correct size) and replace the255/50-17” rears with a tire near 26.25”-26.5” overall diameter (235/50-17”, 245/50-17”, or 255/45-17”). But, do not mount 255/50-17” on the rear (you already know this tire is too tall and does not work with your VDC-equipped car).

--Spike

 

VDC is sensitive to overall tire height AND difference in circumference. Problem is that your Z comes standard with

Bridgestone Potenza RE 040 Summer Tire –
Front 225/45R18 91W,
Rear 245/45R18 96W

VDC is looking for the same specs.

 

David

I think you are comparing the wrong sizes if we are talking about the rear tire.

The rear tire comparison should be a 235/50-17" or 225/55-17" rear size to a 255/50-17" tire (which he has on the car). That difference is close to 3% and less than the 4.5% you mention.

--Spike

 

That won't fix this problem. The OP has mounted the wrong sized-tires.

--Spike

 

I move that every tire fitment question posted on my350z.com should include the tire sizes (front and rear) and the wheel sizes (height, width, and offset; for both front and rear wheels).

Discussion: If we had this information at the beginning of this thread, the question would have been answered almost immediately instead of taking a couple of pages and a lot of wasted space here.

--Spike

 

Spike,

I have stated numerous times throughout the post that this problem has occured with the PROPER 235/50/17 on the rear of the car. I just removed them today and put the 255's back on because they were on the car when I purchased it. The problem also occured with a 245/45/17 on the rear, which is ALSO within the 3%. That's what I'm trying to figure out, is why I was having the problem with the CORRECT tire size all the way around. Nissan can't possibly configure computers based on different rim diameters, it would not be universal enough.

 

Probably a performance or stripped track.

Both came with 18's.
Offset also is important with VDC according to Nissan.
A malfunctioning sensor would act up with the 19's too.
Is the 17's +30 offset?
Nissan did not even allow the LMGT4 on these models without suspension mods.

 

Spike,

All that information was stated in the very first post...check it. Problem never happened with the 19's. What is an LMGT4??? The 17's are a 30mm offset

 

Please forgive me… you do in fact list the tire and wheels sizes in your initial message. I was focusing on your more recent posts in your thread describing a setup and “forgot” that you did provide all the info at the onset. It’s just awful that I’m getting old, careless, and forgetful.

Some other things to check (now I’m guessing):

• terrasmak mentions ABS and worn tires. That could be the problem.
• davidv points out that brake fluid level could cause this (other members have reported this as well).

Forget David's tire chart. He's comparing the wrong sizes (he compares a front tire to a rear tire size to get the 4.5% difference, and that has nothing to do with your situation).

Answering your other question: “What is an LMGT4???” That’s a Nismo wheel, but it has no relevance in this discussion. So you can ignore that as well.

--Spike
______________
EDIT: Well crap, we haven't been able to answer your question, and you need to pass this car to your new buyer.

 

I'll check the fluid level today and see if there's anything else that looks amiss. Guess it'll be back to the stealership, where they won't have a stinkin' clue, or they'll say "everything looks fine".....HELP

 

Wow - I wake up and see that all hell has broken loose in here.

NismoNewbie - go read this post... https://my350z.com/forum/showthread....1&postcount=45

It's obvious you don't have a Enthusiast which means that the car came with 18" wheels. That doesn't really matter as long as the OD of the tires is close to the original stagger.

The computer is working correctly since you had no problems with the G35 wheels, that means that the OD of the 17" tires is outside of the acceptable range.

The 225/50F - 235/50R combo should work as the stagger of 0.4" is well within the "normal" 0.25" to 0.75". No, I can't explain why it doesn't work now.

The 225/50F - 255/50R combo probably won't work as the stagger of 1.1" is too large. No, I can't explain why it used to work and doesn't work now.

The first thing I would do if I was you would be to go out and look at each of your 4 tires and write down the sizes and make absolutely sure you know that the sizes you are stating here are on the proper locations (F/R). You'd be real surprised how easy it is to mount the wrong tire/wheel on the car.

One or more tires sizes is not correct or one of the speed sensors is flaky. Only the Nissan diagnostics can check to see which speed sensor is bad.

 

One more question for you - if you depress the VDC off button and drive around, does the problem still occur?

If so, then it's not a VDC problem but TCS. That definitely points more toward tire size issues or a wheel speed sensor problem.

If it doesn't occur with VDC off, then you might have a problem with VDC unit (yes, I know Nissan checked it) or the wheel speed sensors.

 

newb click top 100 thread

 

Now you see what happens when you take a nap and let the kids play by themselves… unsupervised.

But seriously… the thread loses some credibility for the following reasons:

• NismonNewbie states he has an Enthusiast model with VDC (of course that cannot be right). We don’t really know if he has VDC or just TCS, but then he says the button is labeled VDC, so it’s obviously a VDC-equipped car that is not an Enthusiast model.
  
  
• He also reports mounting three different rear tire sizes (245/45/17”, 235/50/17”, and 255/50/17”). That’s a lot of effort, and not many people have access to that many different tires. If he’s buying 3 sets of new tires for the rear just to get a solution, that’s a significant investment.
  
  
• The problem happened only when swapping wheels. If the tire-sizing is correct, you would not expect this.

His front tires (225/50-17”) are the correct size, and I would expect any of the rears he mounted would probably be OK (the possible exception being the rear 255/50-17” which is a sight push).

I really think this is a situation where we need more information… and I hesitate saying this, but in the infamous (and sometimes annoying) words of davidv: “This thread needs pictures.”

I would like to see the condition of the tires (the fronts and all three rear-sets), and pictures of the sidewalls (the front 225/50-17” and all three rear sets).

My message doesn't get us any closer to a solution, but maybe the request for additional information will help.

--Spike

 

I suspect with all those tire mountings, something got mixed up. That's why I asked him to go check and make sure of what size is where.

 

^^ I agree. He has only one size for the front, so I assume he has that mounted correctly (but, I suppose you could question that).

He must be sweating like a Roman slave swapping all of those rear tires. Certainly it would be very easy to “confuse” the tires and mount them incorrectly.

Here’s what I’ve seen a few times when someone wants to check different tires (sizes, fitment, appearance, tread design, handling characteristics, etc.)

They go to a tire dealer they know well (maybe a relative or a friend) and start picking tires out of the pile that’s going to the shredder. If they want to test different sizes (possibly for gap-appearance or fitment on their car), they grab any tire (and sometimes not even the same brand when mounting left and right and front or rear tires).

Of course doing this won’t provide reliable information about operation.

I certainly do not know if that’s the case here, but buying 3 sets of new rear tires would be a costly experiment.

--Spike