Thoughts on keeping a 33.5" spare with 34.5" tires- Bad idea? (1 Viewer)

[surfishjoe]

Hey gang- did a bit of research and as far as I can tell I "should" be GTG with a slightly smaller spare but wanted to get your opinions. Right now I have 5 255/85/16s which when new measure about 33.5". I recently picked up a sweet set of 275/80/17s which measure out in the 34.5" range with a similar width as my current set. My plan is to keep one of my current tires as a spare because:
1) it fits nicely under my bed
2) because another mtr is around $300 and probably wont fit under my bed
3) I would also have to source a 17" spare wheel

If I used the spare to get off the trail would I be able to engage 4 wheel drive? I know locking the axle with the spare is a definite "no" but could I engage the front dif judiciously just to get back to the parking lot? My drive from RC or AOAA is about 3-3.5 hours if I put the spare on the front would it damage the gears running home on the highway? My truck has ADD so even when the front dif isn't engaged the axles still spin. Please enlighten me on this subject (besides saying don't be a cheap f**k and get a full size spare HAHA).
Thanks

 

[jamarquardt22]

With no lsd you should be good to go. Even the locker as long as the ground is loose should be ok.

 

[drbeemer73]

I run a different narrower WIDTH spare compared to my "on ground" tires, which likely results in my spare being a different diameter. I do that because it will fit in the location my spare goes, under the rear of my FJ60, and it gives me a better departure angle because it does not hang down as much as my "on ground" would, due to the greater width of my on gourd tires..

 

[Cass007]

My new spare is a true 37" vs the ones on the truck (KO2). Figured if I ever had to drive it home I could underinflate it a bit to make it similar sized. Couldn't bring myself to buy 5 new tires just because the sidewall blew in one.

Also, didn't want to get any closer to breaking Avi's record for most tires in a garage.

 

[JeepinPete]

I would do it, but keep the speeds down, since from your differentials point of view, you are going in circles The spider gears have no bearings, they are just a steel to steel bearing, intended for intermittent rotation. If I did the math correctly, your spider gears will rotate 20 revolutions per mile, so at 60 mph they will be turning 20 rpm. Can't see that being a problem.

 

[jamarquardt22]

Like racing stock cars.

 

[surfishjoe]

Thanks guys. I took a tape measure bighorns mounted are right at 32.5” and mtr s are 34.5” unmounted. I imagine once they are mounted with the weight on them they will be slightly shorter. Just waiting on a order of dynabeads to arrive and I will start messing with getting them on and start the cutting.