When I purchased my car 2 months ago the lady had new rear tires put on, but the fronts where near bald. I will be going with a 275/40/18 and a 245/40/18 setup in teh future but I see no point in changing the rears now since they are new.

So if I run a 245/40 up front and the factory size rear (is it a 255/45???)
will I have computer issues???

right now with the bald tires the SLIP is coming on WAY to early in driving situations and its anyoing/scary. Probably due to the bald fronts having a lesser diameter/perimeter than the fresh rears

 

the slip computer is only for the back tires

 

will it mess up the TPS or whatever it is called...its the one that impliments the 3% rule.

 

Additional Information
Location:
Pig Heaven VA


I know absolutely nothing about your car. Do you have VDC?

 

perfect example:
Dry weather warm tires I take a on ramp a little fast, as I am turning I brake. All of a sudden ABS kicks in and makes the car dive forward and the slip light comes on.

It happens mostly on moderate braking...not even threshold breaking at highway speeds around turns.

 

it is an 03 touring manual yes the car should have VDC, traction control the button on the bottom left of the dash.

these symptoms go away when I shut this off

 

No problem, you will be just fine.

 

The difference in circumference is 3.67 percent. That may be too much for VDC.

 

Stock rears are 245/45-18 and yes 245/40-18 will work just fine in the front. Just not on your stock 7.5 inch wheel.

 

tourings dong have 7.5" wheels??
I see tons of pics of people on the 18" 7 spokes with a 245 275 setup.

The front 225 is slightly stretched anyways

 

The stagger is 0.96" - it's not excessive so it should work. There are a lot of setups with 0.9" difference that work fine.

 

Wow… Some misinformation here (and probably because you didn‘t provide full specifications)… OK, best to start with exactly what you have, and go from there. I’m making some assumptions here.

My assumptions:
You have a 2003 Touring Model with a manual transmission, VDC, 18x8” wheels on all 4 corners, and 245/45-18” tires on the rear.

If that is correct:
You can mount 245/40-18” tires on the front and expect great handling with no interference/problem when your car’s VDC is active.

Additional Comments:
Mounting 245/40-18” tires on the front will provide better turn-in and more neutral handling (less under-steer) than the stock 225/45-18” tire. Once you drive on a 245mm (or greater) width tire on the front, you won’t want to go back to the stock 225 width tire.

If in fact you have 18x8” wheels on the rear, you should not mount 275/40-18” tires there. An 18x8” wheel is too narrow for a 275/40-18” tire.


--Spike

 

I have the same car, with factory 6 spoke 18's and my wheels say 7j in the front and 8j in the rear.

 

Here's all you need to know....

https://my350z.com/forum/showthread....1&postcount=45

 

^^ Gosh… why didn’t I think of that (pointing to a thread that provides the information)?

I’ve come to the conclusion there is nothing more miserable than reading a thread that contains short answers with bits and pieces (and often some misinformation).

…And then someone mercifully points to a FAQ thread or an Informational thread providing the facts and answers.

Just about everything the OP asks is in the thread you reference.

--Spike

 

Actually, I just added that one to the Top 100 thread a couple day ago. Seems like the tires size/VDC/TCS question has been getting asked a lot lately.

 

^^ And… it’s another great informational piece.

I believe that the typical Z owner remains with the stock wheel/tire setup, and therefore never experiences significant issues with VDC/TCS.

The Z driver who finds this Forum (my350z.com) is different. This individual wants more from their car, and looks here for help and advice. Wheels and tires seem to be the most popular modification. It’s apparent that mounting aftermarket wheel/tire configurations results in plethora of issues (often involving VDC/TCS).

What is more curious is the fact that Members will mount renegade wheel/tire setups that violate the Z’s VDC/TCS function, and then complain about interference and advise defeating the system (turning it OFF, for example).

Sticky Threads (and we many good ones on my350z.com) are very helpful. New members need to read these. That is how I got up-to-speed on the Forum and learned a lot about my Z car.

--Spike

 

That addition to the FAQ was awesome, short and concise!!!!

So my worn out fronts adn new rears must be the reason for the computer acting up, and at higher speeds that amplifies the difference I imagine.

 

im running the exact same setup with stock rears that your talking about and i have no problems at all and handles great.