Spare Tire Question

brad519 · August 1, 2011

So I'm going out of state this week and need a spare tire. I run 305/70/18 tires on the truck which are 35" tires. My spare tire wheel is a 17" wheel. I couldn't find a steel 18" wheel to use as a spare.

So I can get a Nitto 305/70/17 tire to go on my 17" spare wheel. This one measures 33.8" tall so as long as I put a full size on the back and only use the 33.8 spare on the front I should be good to go right?

Normally I wouldn't run the tire very far but I'm going to Lake Martin in Alabama and that's about a 4.5 hour drive so if I run into bad luck and have to drive the truck home on the spare will it cause any problems if I run it on the front only??

cparks555 · August 1, 2011

I'm in the same boat as you, a buddy of mine told me to run the smaller tire in the rear and two of the same size in the front. Maybe someone can chime in with the correct way to do this.

brad519 · August 1, 2011

I've read it's safer to use the mis-sized tire on the front but I can't confirm that being 100% correct.

My deal is I can get a 305/70/17 to fit the spare wheel that came with the truck and thus not have to buy a new wheel. I would have gotten a steel 18" wheel and just got the same tire I have to use as a spare but that is a 325.00 tire plus the cost of the wheel.

I just don't know how much of a problem I will run into by running the 305/70/17 spare.

cparks555 · August 2, 2011

I think it would be ok to drive to the nearest tire dealer like that, wouldn't try to limp it all the way home though.

BurroWDMS · August 2, 2011

You would be OK running it up front, I would avoid running it in the rear for the diff's sake. You may get an ABS notice up front (or some other warning light), since it will be spinning faster than the 35" tire on the other side would be.

But I have to ask, what is stopping you from getting a 35" tire for the 17" wheel? If it's just a spare, the wheel doesn't have to match what you have on the truck. The truck could care less. 35x12.5x17 seems to be a common size. I looked it up on Discount Tire and it appears that the 35x12.5x17 is cheaper than a 305/70.

Food for thought...

brad519 · August 2, 2011

I can get a 305/70/17 locally for 245.00.

None of the tire folks mentioned a 35x12.5x17 when I was talking to them and I didn't think of it either.

I got a guy who is going to try to find me a 35" for the 17" wheel and I will probably get it cheap.

I just didn't know if running a slightly smaller tire would negatively effect anything.

cparks555 · August 2, 2011

I didn't think of it either, but a 315/70/17 would work great. Maybe look into buying a used one.

brad519 · August 2, 2011

Well happy, happy, joy, joy. I talked to a guy, who talked to a guy, who talked to a guy (lol seriously three times) and he has a 35x12.5x17 used Cooper Tire but looks practically new for $50.00.

So it's cool to run the 35x12.5x17 on the front or the rear should I have a flat...Correct??

BurroWDMS · August 2, 2011

Well happy, happy, joy, joy. I talked to a guy, who talked to a guy, who talked to a guy (lol seriously three times) and he has a 35x12.5x17 used Cooper Tire but looks practically new for $50.00.

So it's cool to run the 35x12.5x17 on the front or the rear should I have a flat...Correct??

Great! Yes, the important factor is overall diameter. Both are 35's, so you will be fine.