Cisco1911

Go easy on me yall.... I have a silly question.....
I recently upgraded tires to BFG KO2s 275/65/R20 from stock Bridgestone's 275/55/R20. It did not don on me until now about my spare tire size which is a an 18" Goodyear Wrangler. I'm not sure of the specks of the 18" spare but I know it can be used with the 20"s otherwise Ford would not have it a spare. I realize my spare can be used with my stock 275/55/R20 tires but I went up a tire size from 55 to 65 which is a taller tire.


Do I need to change my spare tire size to the equivalent of upsized 275/65/R20 or can the 18" stock spare still be ok with the upsized BFGs if I get a flat?


thanks!

lutter5-0

I wouldn't worry about it too much. But when these tires go to get replaced, save one and put it on your spare. Someone correct me if a 34" tire won't fit in the spare location.

cbr600rx7

That's a good question but I would assume it would fit since the raptor wheels fit. However some one with hands on experience should verify. It may also depend on exhaust type.

Cisco1911

Thanks yall for your replies. I'm just concerned that if I DO have another flat (I did have a flat with the stock tires that is why I went with BFGs) the spare wont be tall enough.

berty

I think I read on here somebody who put a 34" tire under there with no issue. But wouldn't worry too much about it, if you get a flat, put the spare on a front tire and take it easy getting to the shop.

akmedic77

This exactly. And don't use 4 wheel drive. The different sizes would be very rough in all rotating components from the differing spin rates.

Cisco1911

Thanks yall. Since I really cant afford a new wheel and tire for the spare at the moment, is there an 18" equivalent tire I can buy and mount to the stock spare wheel so that will not affect the rotating components and also still mount under the truck bed? I much prefer to not risk damage to truck components as I cant guarantee I would be close enough to a place to get a flat fixed.


I apologize for all the questions but I greatly appreciate the feedback.

Spiky

295/70/18 is closest, I think. Check tiresize.com if you want to look at tire sizes quickly.

akmedic77

Find a tire calculator...I think you'll be looking for a 275/85 or so...? Remember that the stock 18" run the 275/65R18 and are still about 1/2-3/4" shorter than the 275/55R20.

I was trying to google off my phone and it's not very efficient. My numbers were an off the wall guess.

lutter5-0

275/75R18 is 34.25" tall. Just a 1/4" taller than your 20's.

Edit, thats not a real size. 285/70R18 is 0.2" shorter than your 20's