Tire stagger

[4 BKT VET]

How much difference can the height of the back tire be from the front without affecting the T/C or ABS?

[sccaGTO]

The rule is typically 10% or less. Whether you go shorter or taller, you can't find too many tire sizes that go outside those parameters. If you are referring to running wider tires in the rear, you can find tires that are wider, but equal in height & not have a problem. This is what most people on this site do.

[4 BKT VET]

Road Test results (T/C on);
Ran a 245/45/17 on the back (25.7") and 245/40/17 on front (24.5).
Drove surface streets normal, no issues or DIC warnings.
Drove freeway to 65++ normal approach, no issues or DIC warnings.
Launched car at 2000 RPM, slight tire spin, DIC displayed T/C but hooked right away.
25MPH in 2nd and jumped on it during a left turn, drivers tire very slight spin for a split second with T/C warning. Barely more tire spin than with all 4 tires the same.
Braking, couldn't find any water, otherwise no different.

[Yeller Jakett]

The real test will be the ABS. I had gotten a used set of wheels and tires on my old M3 a while ago with 245/40 17 rears and 215/40 17 fronts and on the first medium to heavy brake application it was like riding on ice. I know, that's a big difference but be wary... Very scarry!

[Snafu]

It sounds like there is some confusion here so let's clear things up...there are a few different things to look at:

1. Rolling Diameter = the total diameter of the wheel and tire, so rim + (sidewall height x2)

The stock rolling diameter is what the car's ABS systems and such are programmed for. This is the size you want to come closest to...

This is very easy to figure out. Wheel sizes are listed by width in mm / % of width in mm (or profile) / wheel diameter; so a stock setup of 245/45/17 is 245mm wide/ 45% of 245mm = 110.25mm / 17 inch rim. Now to find the rolling diameter, take your sidewall x 2, then divide by 25 (to convert mm to in.) + the rim. So 110.25 x 2 = 221mm; 221mm/25 = 8.84in. 8.84in. + 17in. = 25.84in. -- that is your rolling diameter.

When you increase your rim/wheel size, you need to account for the sidewall by making it smaller so as to keep the overall rolling diameter the same size--that is what your computer is dependant upon.

2. Width = obviously, the width of the wheel/tire combo.

First, don't put a tire that is too wide, on your wheel...you will not get the correct bead and it will lose air at best and be completely unsafe and start to peel off at worst. For example, don't put a 295 on a 8.5" rim...it's just not smart.

Also, keep in mind that because the sidewall number on the tire is a percentage of the width, as the width increases you should decrease the profile to adjust the rolling diameter.

---------------

Staggering

This is done on two levels...

Staggered Width...this is where you run a wider wheel and tire in the rear of the car than in the front. So for example a 245/40/18 in the front and 275/35/18 in the rear (notice that the profile is decreased).

Staggered Width and Rim Size...this is where you run both a wider wheel and tire in the rear, and also a larger diameter rim in the rear than the front. Corvettes come like this stock. An example of this would be a 245/40/18 on the front and 275/30/19 in the rear. If you do the math, reducing the sidewall by 5% should account for the 1" increase in the rim size.


Well, that was alot to write...hope it makes some sense and didn't over-simplify things.

-Sean

[Hada68GTO]

Sean,
There are lots of people on here that run Nitto 275/40 on stock 8 inch wide rims with no apparent problems. 8.5 inch is in the factory suggested range for some 275's. Are you sure about this???

[Snafu]

Sean,
There are lots of people on here that run Nitto 275/40 on stock 8 inch wide rims with no apparent problems. 8.5 inch is in the factory suggested range for some 275's. Are you sure about this???

Sorry bout' that...meant to type 295's...my bad. I fixed it.