Full Size Spare (275/70/18) ?

[Jeff_]

Hey guys hoping to get some insight here.
I know the factory spare is a 17" wheel with a tire that matches the factory size 18" tire (265/65/18).

Being that I have larger than factory tires (275/70/18) I'm curious if I can put a full size spare under the car.

I'm due for a new set of K02's before winter as my current set has 55k miles on them.

But my thought was if I could find a 18" spare wheel I could put the best old tire from my current set on it and mount it up under where the factory 17" spare is.

Because as it stands right now, if I have a blow out or even a flat, I don't have a matching size spare.


Anyone done this? Or anyone know where I can find a spare 18" wheel that'll fit like the 17" does?

Thanks

 

[Jeff_]

If I have to stick with a 17" tire, I'll have to buy one. But the closest match in a 17" to my 18" is a 285/70/17 which is 1.5% smaller in diameter than the 275/70/18.

So that means when driving it will be off by 8 revolutions per mile.

Not sure if that's enough difference to make a difference, and hurt the differential.

 

[Sparksalot]

I have a matching spare on mine. 285/65/18 KO2 on 18x9 wheels.

 

[Jeff_]

I have a matching spare on mine. 285/65/18 KO2 on 18x9 wheels.


View attachment 408896View attachment 408897

Good to know that fits!

Is it an 18" spare wheel you found, or a matching factory wheel or matching your aftermarket wheel?
Was looking for the crappy black stamped steel one. Like this factory 17".

 

[Sparksalot]

Good to know that fits!

Is it an 18" spare wheel you found, or a matching factory wheel or matching your aftermarket wheel?
Was looking for the crappy black stamped steel one. Like this factory 17".

Matching aftermarket wheel. I do 5 tire rotations to keep all of them at similar wear. I also have tpms in each one.

 

[RST Dana]

As long as the diameter is near the factory tires you should be fine. I have a 22 inch wheel with the same tire as the originals in my 2020 spare location.

 

[K2 Kaiju]

If I have to stick with a 17" tire, I'll have to buy one. But the closest match in a 17" to my 18" is a 285/70/17 which is 1.5% smaller in diameter than the 275/70/18.

So that means when driving it will be off by 8 revolutions per mile.

Not sure if that's enough difference to make a difference, and hurt the differential.

255/80/17 is much closer in diameter (0.3% smaller) and will not hang down as much (probably lighter and cheaper as well). Now that you mention this, I need to upsize my spare as well...

 

[Jeff_]

255/80/17 is much closer in diameter (0.3% smaller) and will not hang down as much (probably lighter and cheaper as well). Now that you mention this, I need to upsize my spare as well...

That’s actually not a bad idea either now that you’ve pointed that out. And I agree that it definitely won’t hang as low and will be lighter..
Appreciate the input.