Different size spare tire?

[YSackett]

How close in size does the spare tire need to be in order to prevent causing any damage or issues? I have a 2000 LC that currently has 18" wheels with 255/60R18s, and I'm planning to upgrade to larger tires. However, the spare is a 295/75R16 BFG KO2, and I don't have a spare 18" rim. I'd really rather not pay to replace the current spare setup if I can help it. I am making the assumption that as long as the diameter/circumference are fairly close in size, it won't matter that the spare is on a 16" wheel? How close does the diameter/circumference measurement need to be in order to avoid causing issues?

My top two choices are either a 285/70R18 or a 275/70R18. I've included the comparison to the size of the spare BFG KO2 for comparison.

 

[2020 Rocks]

your spare should be same rim and tire size as the rest

 

[neoworm]

it won't do any damage as long as all your differentials remain unlocked but it's not ideal. It will probably negatively affect your ABS,VSC and TRAC which may cause some drivability issues. It really should be the same size.

 

[awesomeissquid]

If you are only using it as an emergency spare and not going to do a 5 wheel rotation you can order the slightly larger tire for the spare and then have the treads shaved down to make them the same as the other tires. Would depend on how much tread can be shaved off/how much would be remaining and if it can get close enough to the other tires diameters. Is definitely possible, but as others said best case would just be to run the same size all around and then do a 5 wheel rotation at every oil change.