Spare tire size to run?

[adventurenali92]

Hey y’all. Two quick questions….

So I’m running a set of 20 inch take off wheels from a 21’ Denali on my 2006. I’m also running a set of 275/60/R20 Michelin defenders. Absolutely love the setup and the ride on the slightly taller than OEM sized tires for 20s. BUT…. I’m also running GMT900 spec’d front brakes, which requires a 17 inch wheel to clear the caliper and rotor. The problem I’m faced with is that if I get a flat on the side of the road somewhere on either front wheel, my OEM spare wheel is only a 16 inch diameter wheel. It won’t clear my brakes. I have no desire to jack both the front and back axle, put a 20 up front and then put the spare on the back. While I haven’t had any issues to date with flats on the side of the road , thank god, I’d rather be prepared in case it happens somewhere as I’m traveling so much more now in the Denali. Well I think I found a solution, I was junkyard exploring this last weekend and picked up an OEM GMT800 Denali 17 inch wheel and it was cheap. So my thought is can I replace my spare with that wheel and grab a tire that’s either the same diameter or close to the 275/60 tires I’m running on my 20s, so that if I get a flat up front I can throw the Denali 17 on and not have to swap two wheels? First question is there room where the spare goes under the tailgate for a bigger wheel/tire setup? And if so what tire size would be the same diameter or close the 275/60 tire I have on my 20s? I was looking at a tire size calculator on line and I was so confused lol. Never had to think about this before but I’m thinking I’d like to be better prepared in the event of a front flat.

 

[Big Mama]

Here’s what the tire calculator says. Since you’re keeping the same size, or close, you should be fine fitting the spare.

 

[swathdiver]

Hey y’all. Two quick questions….

...running a set of 275/60/R20 Michelin defenders.

picked up an OEM GMT800 Denali 17 inch wheel and it was cheap. So my thought is can I replace my spare with that wheel and grab a tire that’s either the same diameter or close

A 255-80-17 will be functionally the same height as your Defenders and should fit easily up in the spare tire well. A 265-70-17 would be over an inch shorter.

 

[adventurenali92]

Here’s what the tire calculator says. Since you’re keeping the same size, or close, you should be fine fitting the spare. View attachment 409001

New spare is a 17 inch wheel not an 18….

 

[adventurenali92]

A 255-80-17 will be functionally the same height as your Defenders and should fit easily up in the spare tire well. A 265-70-17 would be over an inch shorter.

I did see the 255-80-17 on the calculator and thought that might be the route to go but wasn’t sure. Thanks for the confirmation. Would that width tire cause any issues with my stabilitrak or diffs given that it’s not quite as wide as the 275s? Just wanna make sure if I have to run a spare I don’t mess anything up with my AWD or stabilitrak systems.

 

[swathdiver]

I did see the 255-80-17 on the calculator and thought that might be the route to go but wasn’t sure. Thanks for the confirmation. Would that width tire cause any issues with my stabilitrak or diffs given that it’s not quite as wide as the 275s? Just wanna make sure if I have to run a spare I don’t mess anything up with my AWD or stabilitrak systems.

Width wise it won't matter, it's the height that could be a problem. That tire is about 1/16th of an inch taller than yours and of course would have a larger spread as your tires wear down, maybe 1/4 inch at half life. Unless you bought one used with less tread. AWD systems don't like more than 3/16 of an inch difference if I remember right.

You could also just get a 20 inch wheel and put the same size tire on it as your Defenders. The size is popular enough you could probably pick up a slightly used Defender to match and it ought to fit without modification. On the GMT900s, the trucks running 22" wheels used a shorter hoist to accommodate the wider wheel.

 

[adventurenali92]

Width wise it won't matter, it's the height that could be a problem. That tire is about 1/16th of an inch taller than yours and of course would have a larger spread as your tires wear down, maybe 1/4 inch at half life. Unless you bought one used with less tread. AWD systems don't like more than 3/16 of an inch difference if I remember right.

You could also just get a 20 inch wheel and put the same size tire on it as your Defenders. The size is popular enough you could probably pick up a slightly used Defender to match and it ought to fit without modification. On the GMT900s, the trucks running 22" wheels used a shorter hoist to accommodate the wider wheel.

Ok good to know on the size difference. Gonna research that now.


20 inch wheels are expensive…. And so are Michelin defenders in my size…. Not dropping that much for a spare…. Hence the cheap 17 inch wheel from the junkyard….. lol.