Beware of factory spare with larger tires

[MaxRock]

One of my 255-85x16 Dunlop Radial ATs seperated on me last week. Fortunately, I stopped before the tire blew out, as it was on the front of the truck. I mounted my factory spare in its place and went on my merry way. After about 3 miles, my anti-lock brake light came on.

I speculate the ABS computer was detecting a significant difference in tire speed between the 245-75x16 (factory) and the 255-85x16 (Dunlop). The computer could not compensate for the difference in tire speed and flashed the ABS light.

I had the tire dealer change the spare for a 255-85x16 so now all 5 of my tires are the same size.

Has anyone else experienced this?

MaxRock

[SoCalDMAX]

Hmmm, verrry interesting.

I bought 5 Dunlop A/T 255/85s figuring that if I were to ever need it, the right size spare would be nice. 3 out of the 5 separated on me as well with about 10,000mi on them. They didn't go flat, but rolled like an egg. Discount Tire replaced 4 of them with Rover RVs (so they'd be the same mileage) and Ride Matched them, blah blah at no charge. The remaining A/T is the spare.

This might be like a Firestone kinda thing. They had to use the Hunter GSP9700 to find the problem. Perhaps it would be good to have the rest of the tires checked as well. Keeping the shiny side of the vehicle up always makes me happy.

Regards, Steve

[Silver Bullet]

Eventhough the ABS light was on, were you still able to "limp" with one shorter leg without any problems?

[Spoolin'It]

MaxRock,
I think you hit the nail on the head, the ABS computer saw a higher wheel speed on that tire and assumed the sensor was going bad and threw a code. When you fixed the tire everything was normal again so the light went out. If the computer was scanned there would stil be a code there for that wheel.

Silver bullet,
The only problem with doing this would be the ABS is inactive while the light is on. Once the tire is replaced it should sense all is right and go back to normal. The smaller tire should always be placed on a front wheel since a mismatch in the back would cause big problems in the rear diff.

[INDI-GO]

So if you still have a factory spare left after you have gone to a different size on the ground, and you have a 4x4, can you still safely mix the factory spare on the front?

Naturally not when in 4wd.

I think I would change all 5.

???

[HotShot]

If you want to save a few bucks and make your spare a little less interesting to theives then get a used tire put on that rim but make sure your spare matches in size will save a few headaches.

[MaxRock]

I placed the 2 new tires (replaced the seperated tire and spare) on the front and picked the best 2 remaining tires for the rear. The tire with the least tread was used for the spare. The ABS code cleared after placing the correct size tires back on the truck and restarting the engine. I did do a brake check and the ABS is working.

This is the only truck I have ever owned that I have to rotate the tires to keep them off of the BACK! :D ! I find it very difficult to take off, when merging into traffic from a stop sign/red light, without experiencing some tire spin. I didn't realize how much the rear tires were wearing until I compared them to the new ones! I have recently started taking of in 3rd instead of 2nd, trying to reduce tire spin. Ain't torque wonderful. Well, if you are going to have a complaint, this is a good one to have!

MaxRock