Jazzer The Cat

I spend a lot of time answering questions here on tires/fitment etc..... and this comes up frequently.

I know that running tires off different diameters on front/rear can cause ABS "issues", as I have had some myself. Can anyone give us a nice practical explanation of how much difference becomes a problem and how can it be addressed? How much difference does it take and exactly what are the implications of running say a 25" tire (f) and a 26" tire (r)?

EDIT: Just did LOTS of research all over the Net and found TONS of info on ABS. I found lots of posts and mentions of the misc. issues that arrise from different diameter tires, but no body could say at what point the ABS system will have issues and how exactly they affect everyday driving. I am sure different manufacturers will be affected a little differently, but no idea how much. Norm and I have spoken on this issue prior, but hoping he will chime in with some max limits and such.

Jazzer

colin@tirerack

I had our tech dept field your question. Here is their reply:

Unfortunately the vehicle manufacturer’s don’t provide this guidance and Tire Rack has seen tolerance variations within a single vehicle make/model/year.

If the vehicle is engineered to use the same size front/rear, we suggest fitting front/rear tires with the same diameter (even though they may be a little different than the Original Equipment size). If the vehicle came with a staggered setup, maintain the same overall/diameter percentage front to rear.

Additionally, even if installing a staggered tire size setup (of different diameters) doesn’t cause the electronic driver’s aids to shut down (as identified by a dashboard warning light, it may cause the ABS, traction control or vehicle stability systems to operate less efficiently.

Jazzer The Cat

Thanks, Colin

That is kinda what I was thinking, just wish there were a set diameter differential that would be easy to determine. I know my own ABS light comes on a bit easier with my staggered set-up. It obviously can be done, just look at the Chrysler Prowler .

Jazzer The Cat

Stoenr

Not sure if this will help any. But at the drag strip I run approx 27" tire up front
and 25.7" tire in the rear. Never had an abs issue, or a light come on.
These rear are installed at the track, and not driven to the track in this condition. But I figure they get about 8-10 miles in that situation on a track day.