Stillen Z

iTrader: (2)

I'm trying to figure out if a wheel/tire combination that I'm thinking about will work or if it will cause problems with the VDC computer or with the ABS system. Yes, I carefully read the Sticky https://my350z.com/forum/wheels-and-...read-here.html

But, I'm still not clear on a couple of things. It seems that as long as I don't vary circumference from OE by more than 3% on the fronts alone, I'm okay. Ditto for the rears. Here is where I am uncertain: if the variance from OE on the fronts is less than 3% and the variance on the rears from OE is also less than 3%, but the front variance plus the rear variance is more than 3%, is that a problem?

Specifically, if I fit new tires in the front (245/40-18s) that are 1.2% smaller than OE and new tires in the rear (295/30-19s) that are 2% smaller than OE, neither end is more than 3% different from OE. But, the total variance is 3.2%. Will that cause problems?

Also, if a tire size variance is enough to cause problems, will it affect only the VDC computer or will it also affect the ABS?

Anyone out there know the answer?

davidv

iTrader: (2)

Hoosier R6 Radials is a road racing tire. Not sure why you would consider driving with VDC ON?

Stillen Z

iTrader: (2)

I don't plan to drive with VDC on with the R6s, something I'd said in the second to last paragraph when I said:

"Also, if a tire size variance is enough to cause problems, will it affect only the VDC computer or will it
also affect the ABS? If it only creates problems for the VDC, I can solve the problem by turning off the
VDC when the R6s are fitted and turning it back on when normal tires are on. Something I'd do anyway."

Still, I wasn't very clear on that point so I think I'll edit the post to fix the ambiguity. And the question still applies in any event because I also plan to buy road tires and I think I will run into the same size issue.

Either way, I still need to know whether tire diameter can cause problems with the ABS.

davidv

iTrader: (2)

Rear tires are 6.4 mm taller than front. I would prefer to see 10-20 mm.

cdoxp800

iTrader: (12)

Here is a good tool for sizing

http://www.wheelsmaster.com/rt_specs.jsp

Stillen Z

iTrader: (2)

I have various sizing tools already. I know how much smaller what I want to fit is compared to OE. What I need is a clarification of, or further explaination on, the post about the 3% rule https://my350z.com/forum/wheels-and-...read-here.html .

Here are the two quesions:

1) If I fit new tires in the front (245/40-18s) that are 1.2% smaller than OE and new tires in the rear (295/30-19s) that are 2% smaller than OE, neither end is more than 3% different from OE. But, the total variance is 3.2%. Will that cause problems?

2) If a tire size variance is enough to cause problems, will it affect only the VDC computer or will it also affect the ABS?

DavesZ#3

iTrader: (26)

Try this one instead...

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

Stillen Z

iTrader: (2)

Hmmm. The tires I have in mind have only a .4" stagger front to rear. Back to square one.

DavesZ#3

iTrader: (26)

0.4" would be well within the limit of 0.25 to 0.75".

Stillen Z

iTrader: (2)

But, the post in your link says: "When choosing new tires, try to find front/rear pairs that maintain the stagger of at least ½" and less than 1". You should also look for front/rear setups that maintain the same OD as that will keep your speedometer and odometer accurate."

So at .4", I'm .1" outside of what the computer will apparently tolerate.

DavesZ#3

iTrader: (26)

True but the OEM 17" setup was only 0.4" and it worked fine. Originally, the recommended range was 0.25 to 0.75", later it was revised up because some cars were more sensitive than others and tire wear would lower the gap in some cases.

Stillen Z

iTrader: (2)

Well, then, it looks like the set up I have in mind with .4" stagger should work just fine. Thanks.

Do you know if the ABS also is affected along with the VDC by tires that are outside of the stagger acceptable to the computer?