My SD f350 has 20 inch Michelin tires and when I arrived home I started to look it over. Got the creeper out and crawled around under the truck and noticed it had a 18 inch Goodyear spare tire. That's not right is it ?

 

Perfectly normal. Wheel size isn't the issue, it's tire diameter that has to be the same.

 

They all come with 18" with steel wheel. It's no problem since it's a full size and can carry any load you may have and it's only temporary.

I normally drop my spare and flip it over with the valve stem to the rear so twice a year I can slide under the rear and check the air and put some in to keep it at pressure. Can't do that with the stem up top. I didn't do it because the alarm gizmo was attached and did not feel like fooling with that.

 

Ok... so thanks for the info. I did notice the tire is larger size for 18 inch tire and figured it would be close to my size on the truck. Thanks guys

 

The issue that I see is that I have 275/65/20 on my truck and these are 34.2 inches and the spare is a 275/70/18 and that is 33.2 inches. I know this would not pose a problem in 2wd on the front but if I had to go some distance with it on the rear or on the front in 4wd I would think the diff in the axle would think I was going around a turn the whole time. Sort of not so right for this price truck, but so it goes, I picked up a spare 20" wheel and mounted a 275/65/20 it for some of my long distance back country trips.

I noticed this as soon as I bought the truck and it looks like there is not room for anything much larger than a 33.2 inch tire under the truck, maybe you could squeeze one bigger but it would be tight at best.

 

Should not have nothing to worry about unless you have limited slip rear.

 

Would be nice if you can use that spare in your tire rotation. Or if you ruined a tire you could use your spare tire as the forth tire. But whatever ,,a $70,000 truck I would like a spare tire the same inch size (20 inch) as my 4 other tires

 

Me too. I typically buy a fifth wheel and tire and do a five-tire rotation.


Actually, I recant that. Since the truck only monitors the four TPMS sensors, you'd still have to repair/replace the flat tire to get rid of the TPMS light. So five tire rotation doesn't seem like the way to go (my 4Runner had TPMS in all five tires but didn't monitor exact pressure). Due to my OCD, I'd still be inclined to get a right-sized steel wheel/tire for spare use.

 

This seems like as good place as any.

Does anyone with a Diesel Plat want to go in and buy a set of 4 take off's from someone? I'm thinking of trying to do this so i can have a full size identical spare.

Will our standard wheel fit in the spare tire location? Usually that is a must because if you need the spare, you need to put the flat tire back into the spares location. I understand we have a truck and bed, but what if the bed is fully loaded?

 

How many $100,000 sports cars have a full size spare? I'll guess that none of them do. Last car I purchased has a bottle of fix-a-flat and small air compressor as a "spare". With over 1 million miles of driving, I have not pulled out the spare in over 25 years in any of my vehicles. Anymore, I just pull the offending nail or screw, plug the tire and re-fill it all while the tire is still on the vehicle. It's a 10 minute job. The tire size difference being worried about is also miniscule. If it really bothers you, just drive around the block, left or right depending on where the smaller tire is, and it will even things out in the differential.

 

Says right on the door sticker what size the spare is.. I wasn't surprised at ll.

 

I just wish my other 4 had the aggressive tread of my Goodyear spare. lol Makes them look like racing slicks.

 

i just looked under my truck. i was curious if i could get a 35” tire under there since I just got that size tires.

it looks to me like there is a good 1-2” of clearance around the entire tire, i have the 275/70-18 (33.2”) spare. I be I could get a 35 under there.

has anyone tried?

 

This is unusual to me. So does the trucks with 18 inch Goodyear tires have a 20 inch spare???

 

And that was the issue on the 08-10 trucks. If you had a flat in the rear, you had to put a tire from the front on the rear, and put the spare on the front.

don't need to do that on the 11-17's, but still, I don't like the idea of pulling a heavy trailer with a smaller wheel on one side of the rear axle. I'll be getting a fullsized spare.