Spare Tire Size Question

Hi guys,

I'm currently running 285/70/17 tires. I want to slap a bigger tire on my spare 16" wheel, possibly 285/75/16. I know the tires are almost identical in size but was wondering if there would be any issues if I chose to go this route. I've heard some saying that it's best practice to use the same size tire for the spare, but the 285/75/16 will just be used for emergency. Is there anything I should be concerned about when going this route? Any input is always appreciated. Thanks!

 

Theoretically the two tire sizes differ by 0.12" in diameter. In reality there is no enforced industry standard on tire size tolerances, so even two tire brands both advertised as 285/70/17 can differ by more than 0.12". The difference IS big enough to cause extra wear in the rear differential and potentially cause VSC/ABS to malfunction, so it isn't advisable for long-term use. For spare use, it's fine.

You only challenge may be physically fitting the larger 33" spare in the 31" cradle on the underside of the frame. You may need to open up the cradle a bit with a big hammer. (I suppose you can also carry it slightly deflated and carry an air pump all the time, but that will be extra hassles if you get a puncture on the road.)

 

Thanks for the reply. I'm only looking to use it in emergency situations and just wanted to make sure this will not be bad for the vehicle for short term.

Yeah, I was reading some threads about fitting it under the frame. I shouldn't have an issue hammering away at those retaining brackets. I do have a concern about relocating the tire pulley system back one inch.