I just got my new rims and tires two weeks ago, and I am now noticing that when I turn the "SLIP" starts to blink whenever I take turns. And before I use to be able to take turns easily, and now with the new wheels and tires its showing "SLIP" and its happening on even the slightest turns, the same turns I took before going faster than I am now. Do you think this could be some sort of alignment when they put the tires on or something, or maybe the tires are just wrong with my car.

Need help!!!
Thanks....

 

size of tires?

I believe that it is requried that the rear tires are about half an inch or more in diamater then the fronts...

i forget the exact number..

but its in the FAQ

 

You CANNOT put a tire on the front of a 350Z that is any taller than the rear. The most common problem is when you put a 45 series on the front and a 40 series on the rear. Oh.....and did I say that you CANNOT put a taller tire on the front than on the back??? I think that's what I said. Yea....that's what I said.

Happy Motoring........

 

HJmm, front tires are 245/40 and the back are 275/35...
So, is that whats causing it, the 40 is in the front and the 35 is in the back?

 

This needs to be sticky. A lot of people make this mistake. Who sold you the wheel tire combo? They need to be castrated.

 

What do you mean, "This needs to be sticky? IT was a place in Tampa, FL, called Racing Zone. ANd they have done lots of 350z too. So, whats the word, they shouldnt have put those size tires there on the car or what? Why do they need to be castrated?
I need to go back to them as soon as I can so I can get this problem fixed so I don't get into an accident or what not..

Thanks!

 

if the rim/tire combo is litter then stock rims/tires and the diamentions of the tires are different. the VDC will have problems, not major and i wouldn't worry about it. you can do a search on the forum and get more specific details why, but that is the skinny

 

I don't care where you got the wheels and tires for your Z but they DID NOT KNOW DICK.............Like I have said on these forums at least 6 different times, YOU CANNOT PUT TALLER TIRES IN THE FRONT. You will either have to put 40's on the rear just like the fronts or change the fronts to 35's to match the rears. I would suggest going to 40's all the way around. The knuckleheads that are going around selling those offset tire sizes don't know about the traction control systems in the Z.

I hope that explains things a little better.

Happy Motoring................

 

Weight has nothing to do with it. There are numerous people on this board running a lighter rim/tire combo with no problems.

 

mechanicly the VDC operates on a multitude of sensors, but atleast 4 of those sensors are likely measuring the speed each wheel is turning individually, thus it can sense differences. but it must have a "constant" something to compare it to, it uses the stock rim setup to get this, and more importantly a ratio of them, side to side should be the same, front to back should be X different.

but now instead of the backs being say .5" taller they are .1" smaller(made up numbers), so it feels like the backs are spinning faster than the fronts, and tho I have no idea what it might do as a correction, it will have a feeling that you are losing traction in back and thus the slip light and perhaps corrective action. and my guess is that during the turn these factors are somehow worsened.

your best bet is to take the fronts down to a 35series if your running 19" or take the backs up to a 40series if your running 18"; that will solve the problem. you may choose to wait till the tires need replacing, the setup should not cause any damage, its just not the ideal sizing.

 

I just got new rears on my track 255 45. This was taller than stock. Slip lite came on occaisionally. So I said **** it and went to 255 40 and had them replaced. the 255 40 is shorter than stock but still has a taller overall diameter than the front tire. Looks much better with a shorter sidewall too. Me like!

Problem solved right? wrong. Slip light still comes on every once in a while especially when driving spiritedly. I used to turn the VDC off sometimes. Now its always off! I dont want to risk having VDC cut my throttle when I m trying to pass a semi from an on ramp with a guard rail. Now I have to look at that stupid yellow lite and night

My point is this: You guys are talking about switching the aspect ratio and that does not mean sh*t. Thats what I did and I had problems either way. You need to use the formula to determine the overall diameter of both tires. Aspect ratio is the tires sidewall percentage versus the width of the tread.

So obviously if you have a 245*40 tire, its not the same overall diameter as a 255*40.
Because I changed the width of my back tires only, I was not able to maintain the exact stagger. When i change my fronts I will add ten mm of width to the front and subtract 5 off the aspect ratio like I did for the rears. It doesnt have to be this hard but use the below formula when switching tires to maintain stagger rather than juggling with aspect ratios like I did.

Here

From this you see that changing width is not so easy for us with vdc because once you change width on tire it is very hard to get the same diameter back.

Fukn confusin isnt it?

I would like to choke whoever came up with that formula

 

yes small changes wont net the proper size, tho your small change to a 255 should not have caused any problems thats a 4mm difference kinda small.

but the 275/40/18 and 275/35/19 are extremely close to stock, just how it works out. I have had the 18" size on my car, and never seen the slip light when I shouldnt have.

 

So, what ever i do with putting 40s in the back the 35's the front, it might not fix the problem? Im taking my car in to Nissan tomorrow to see what is happening. I told them my situation, and they will take a look at it. But I am also going to suggest them take the car for a spin around the area so they can feel and see what im talking about, instead of assuming what is going on.

With the ratio... one of the guys here at my work, who is alos a Z fan, he has a 240sx, still family, he was saying that they did a good job with the wheels, and that the 245/40 in the front is right b/c its 40% of the 245, which would be less than the 275/35 since its 35% of the 275 so it shouldnt matter... I just don't know what to believe anymore.... Just confused.

What are the tire sizes for those who have 18s? Plus I dont have VDC, I have the Enthusiast model which originally came with 17's on it... does that make a difference?

 

Well explain this, when i had my stock rims i couldn't just step on the gas in 1st and get the tires to come loose, the slip light will come on right away and tracktion control with handle it.

now with my 19"Gt7's with 245/35/19 front, 275/35/19 rear
wider tires, but same circumference, i can get the tires loose for a full 2 seconds before the slip light comes on and the VDC takes over. My tires are wider then stock and also lighter

 

I would say the proper sized tires for the 18's on your car would be 255/40/18's front and 275/40/18's rear. This would give you a front tire with a diameter of 26.1" and a rear with a diameter of 26.6". The original 17 inch tires were spec'd as being 25.9" tall on the front and 26.3" on the rear.

I have run the following tire combos with no problem on an Enthusiast Model:
245/45/17 front with 255/45/17 rears
245/45/17 front with 285/40/17 rears***
275/40/17 front with 285/40/17 rears

*** not reccomended due to more understeer than stock, Just not a balanced setup. But no slip light problems.***

 

Go to this link:

http://www.discounttiredirect.com/di...foTireMath.jsp

Compare your standard tire to the new ones. What is important is the revolutions per mile ratios from front to rear (left to right). This is what TCS and/or VDC will be sensing.

Standard OEM size for 17" rims are 225/50 front and 235/50 rear with the rear doing about 12 less revolutions per mile.

Compare front to rear of new tires. Using the rear as the second number then you should get a negative number for revs per mile. Since you had 17" rims as OEM I would try to stay as close to -12 as possible.

Note that 350Z-RED using 245/35 fr and 275/35 rear on 19" rims has the rears going about 25 revolutions slower. Twice the number for OEM 17" (this may explain the slow onset of slip).

Standard OEM size for 18" rims are 225/45 front and 245/45 rear with the rear doing about 21 less revolutions per mile!

The calculator is a SWAG because different vendors tires may differ. Check the manufactures numbers and compare these to the ones from this calculator.

Good luck.

 

Come on guys....you don't have to have a mathmatic degree and it certainly isn't rocket science. If you really want to feel like a genius, take one of your front wheels off and roll it down to the rear of your car and see if the front tire is taller. If you want, place a wooden ruler or something similar on top of the tires to see if one is taller than the other. If the front tire is taller than the rear, the slip light will come on (usually during a moderate turn versus one of those drifting turns we love to take). I don't care if your front tires are 4 feet wide, THEY CAN'T BE ANY TALLER THAN THE BACK ONES. I own a Z Roadster and have also designed traction control systems for Roush Racing. The traction control system on a Z is not that complicated. Momentary slippage (burning out) is built into the system. When you have a taller tire on the front, the traction control system gets a constant reading that the rears are slipping. This overides the momentary slippage situation and when you go into the turn, the system activates and controls the throttle until it senses that danger has passed. If there are Z owners that have shorter tires in front, and the slip light continues to come on, you either have a defective traction control modual or a faulty wheel sensor in the rear end.

 

sarcasm82 asked about the slip light coming on too early not too late. Which has nothing to do with running lighter rim/tire combo.

 

Doesn't look like anyone yet gave you a definitive answer on tire sizes for 18" rims, so I'll chime in. (Wait, looks like one or two people did, but I'll chime in anyway.) You didn't list the width of your new rims, so I'll have to generalize. The most common tire size people are running is:

245/40/18 front
275/40/18 rear

These tire sizes are ideal for an 18x8.5" front rim and 18x9.5" rear rim. If your rims are much wider than this, you'll have to check the tire specs to make sure they are compatible with the wider rim.

As far as diameter difference between the front and back tires, from what I've read on this site, the rear tire should have an outer diameter .5" to .75" taller than the front tire. This may or may not be true, but it seems to be what I keep reading on this site. Someone mentioned a FAQ that had the correct info?...

Ah, the FAQ was stickied to the top of the forum. Here's the link:

https://my350z.com/forum/showthread....threadid=37901

 

I'm running 245/35/19R in the front, and 275/30/19R in the rear and I don't have any problems with 12000km on the car.