Space saver spare tire on my 2012?

[kcpolk]

I'm at 42k on my 2012 Laramie... she is on her second set of Firestones (from the original owner)..... I'm waiting for the new Michelin Defender LTX tire to go on sale at Costco. Anyway, the tires on my truck are LT27570R18's on 18" OE alloy wheels. When I search tire suppliers for 2012 RAM 2500 the all come up with LT26570R17. Also, door jam decal shows 26570R17. My spare tire is 26570R17. What's up with that? Did someone change out 17" wheels for 18"s? Weird. Anyway, my plan is to go with the 27570R18 Defenders. However, if I get a flat..... I know I shouldn't use the smaller 26570R17 spare tire in conjuction with my 27570R18s.... especially on the rear, this would be hard on the limited slip diff. So, I need to find an 18" steel spare wheel and mount up a 27570R18 tire. It looks like I have enough room to fit a spare 27570R18 tire between the rear diff cover and the bumper. Anything wrong with my logic on this?

 

[Grizzly]

I see nothing wrong with your thinking. On the other hand, if you use the spare tire on your truck, the 265 70R17 for a short time while you get the 275 70R18 tire fixed, won't hurt anything. It may hurt if you drive on for 200 miles.

 

[Hoefler]

The spare is the same physical size as the as the 18"s on the ground

 

[gsbrockman]

The spare is the same physical size as the as the 18"s on the ground

LT265/70R17's are approximately 31.9" OD and 659 revolutions per mile.

LT275/70R18's are approximately 33.2" OD and 627 revolutions per mile.

 

[kcpolk]

Thanks GS...... if I got an LT275/70R17 tire for my spare 17" rim.....I wonder if it would be even closer in diameter to the LT275/70R18's?

 

[gsbrockman]

Thanks GS...... if I got an LT275/70R17 tire for my spare 17" rim.....I wonder if it would be even closer in diameter to the LT275/70R18's?

Looks like a LT295/70R17 is 33.3" in OD and is closer to OD of your 18's.....

 

[Newsa]

18 inch OEM rims are a little over $100 on ebay. Minimal to no shipping

 

[kcpolk]

Thanks for the advice everyone..... I ordered an OE 18" wheel and tire on eBay. So, now I have a brand new 17" steel wheel spare with factory Firestone LT265/70R17 tire that HAS NEVER BEEN ON THE GROUND. I have it up for sale...... anyone interested please send me a P/M.

 

[gsbrockman]

Thanks for the advice everyone..... I ordered an OE 18" wheel and tire on eBay. So, now I have a brand new 17" steel wheel spare with factory Firestone LT265/70R17 tire that HAS NEVER BEEN ON THE GROUND. I have it up for sale...... anyone interested please send me a P/M.

Might be a tough sale......if it's going on 5 years old, I'd not trust it for a long amount of time.