Getting a matching spare for upsized tires: what is Jeep's spec for a 'match'?
I have upsized my tires and I need to upsize my spare tire so that its circumference (or OD, or RPMs / revs per mile) matches the other tires. If they don't match, then the 4WD system will sense the difference and might think there is slippage and will want to compensate - not good. The question is, what is Jeep's specification on how different the tires can be and still 'match', and where is that documented? For example, must the RPMs be within 5% of each other? I imagine that specification is defined for each 4WD system. I have Quadra-Drive 2 on my 2016 WK2.
For Goodyear Wrangler Duratracs:
275/55-20: 31.9" O.D., 655 RPMs - I have these tires mounted
255/70-18: 32.1" O.D., 651 RPMs - the spare tire I plan to get, on the OEM 18" wheel
Those tires are probably close enough to be a match, but I want to know what the Jeep requirement is. My current spare is 10.5" wide, and the Duratrac spare would be 10.2" wide, so it should fit in the spare tire case, and the case's lid should close fully flat.