fyi on silverado duramax 2500 spare tire

[Jerry Davis]

I purchased a new 2024 Silverado 2500 HD Duramax last year. I was hearing a rattle and thought it was something in the tool box. But decided to check under the truck to see if maybe the spare tire was loose. It was ok, but the tire size was 275/70R18 and the other tires are 275/65R20!
I called the dealer where I purchased and left a voice mail that I wanted the same size tire, waiting on a return call.
I cannot see how this would be normal? That would have been a dealbreaker for me, if it is.
Has anyone experience such?

 

[JKellerJr]

Its not clear on the Chevy website. I found this on the Duramax forum (this guy says he works for GM):

As long as the spare is within 3% of standard tire and proper load capacity, you aren't going to have problems. Only the AT4X and ZR2 get matching spare tires. A 20" steel wheel weighs alot and 20" aluminum costs alot so you get a 18" steel.

https://www.duramaxforum.com/threads/spare-tire.1032653/?post_id=12569025#post-12569025

 

[JKellerJr]

A quick google search shows it looks like Ford's & Ram's are much the same.

 

[Riverbug]

Yep, that's common. The radiuses are pretty close so it doesn't matter from that perspective. However, I did buy a 20" rim and tire for my F350 that matches the others so that I can include the spare in tire rotations and I can remove one at a time, and if we had a blowout on our extended trips I could drive on a matching wheel for a period until I got the blowout fixed. But you definitely do not need to invest in a 20" rim for the purposes of have a spare with a matching radius to the others. You've already got one. Congrats on the new rig!

Edit: In case it is not understood. You see the difference in tire height...70R18 vs 65R20? That's how they get the same overall radius size even though the rims are a different size. So, if one fits in your spare tire location, so would the other provided you also replaced the tire if you purchased a 20" rim. Thought I would add that detail in case it wasn't clear.

 

[Capt Bob]

I purchased a new 2024 Silverado 2500 HD Duramax last year. the tire size was 275/70R18 and the other tires are 275/65R20!

Has anyone experience such?

While we don’t have a Dmax, we do have a 2024 2500HD that has the same size tires as yours. This difference has been discussed before on the GM Forum I’m a member of and it’s common. The 18” rim is pretty tight fit.

 

[Jerry Davis]

Yep, that's common. The radiuses are pretty close so it doesn't matter from that perspective. However, I did buy a 20" rim and tire for my F350 that matches the others so that I can include the spare in tire rotations and I can remove one at a time, and if we had a blowout on our extended trips I could drive on a matching wheel for a period until I got the blowout fixed. But you definitely do not need to invest in a 20" rim for the purposes of have a spare with a matching radius to the others. You've already got one. Congrats on the new rig!

Edit: In case it is not understood. You see the difference in tire height...70R18 vs 65R20? That's how they get the same overall radius size even though the rims are a different size. So, if one fits in your spare tire location, so would the other provided you also replaced the tire if you purchased a 20" rim. Thought I would add that detail in case it wasn't clear.

I still believe they should be the same size tire

 

[Jerry Davis]

It is a deceptive practice to me, and also I have (4) 20 inch Goodyear and the spare is an 18-inch Michelin, different tire size and tread pattern

 

[JKellerJr]

It is a deceptive practice to me, and also I have (4) 20 inch Goodyear and the spare is an 18-inch Michelin, different tire size and tread pattern

IMO while it would be nice to have the same tire I don't know if I consider it deceptive. Cars haven't come with a matching spare in as long as I can remember. Although that has as much to do with space constraints as a cost cutting measure, its still been the standard. Why should trucks be any different? As long as it does its job, getting one down the road in an emergency situation, its doing the job it designed for.

If you want to use it in a regular rotation schedule then you need a matching rim unless you want to remount every time. Its an easy, although costly fix, to do as @Riverbug did and buy a matching rim and tire.

I'm admittedly probably less concerned then most since I've been extremely lucky over my almost 40 years of driving to have never had to change a tire on the side of the road. I'm pretty sure the only time I've even pulled a spare is on our current trailer to replace a tire due too odd wear because of an alignment problem. Luckily the RV came with the same tire just on a standard rim.

 

[JKellerJr]

So, if one fits in your spare tire location, so would the other provided you also replaced the tire if you purchased a 20" rim. Thought I would add that detail in case it wasn't clear.

Since the ZR2's and AT4X's come with a matching spare and they have the biggest of all the tires available, I would assume the spare location should fit the 20's without issue. I doubt they have a different location set up than the rest.

 

[Jerry Davis]

IMO while it would be nice to have the same tire I don't know if I consider it deceptive. Cars haven't come with a matching spare in as long as I can remember. Although that has as much to do with space constraints as a cost cutting measure, its still been the standard. Why should trucks be any different? As long as it does its job, getting one down the road in an emergency situation, its doing the job it designed for.

If you want to use it in a regular rotation schedule then you need a matching rim unless you want to remount every time. Its an easy, although costly fix, to do as @Riverbug did and buy a matching rim and tire.

I'm admittedly probably less concerned then most since I've been extremely lucky over my almost 40 years of driving to have never had to change a tire on the side of the road. I'm pretty sure the only time I've even pulled a spare is on our current trailer to replace a tire due too odd wear because of an alignment problem. Luckily the RV came with the same tire just on a standard rim.

I cannot predict when I may have a flat, not as lucky as you. Im 73 years old and have had several flats over my driving. You could be on the road and may have to drive hundreds of miles on a weekend to get a tire repaired .
I did talk to the dealer where I bought the truck. Not only the spare being different size it is a Michelin and Goodyear all around. The sales manager agreed with me that they should be the same size. He said that is how GM does it with smaller size. He told me to contact Chevrolet customer care, which I did. They opened a case and will get back to me.
I will keep the board updated on outcome

 

[Capt Bob]

I’m 74 and I still remember when having a spare was a luxury. We street rodders were happy to have a rim that matched the bolt pattern. Our front tires were much thinner than the rears and no one carried a cheater slick for a spare.
That stated, I understand the need for a spare comparable to what one runs on their TW. Comparing my situation, I have Goodyear Wrangler 275/65R/20s on the truck and a Michelin 275/70R/18 for a spare. I do not rotate the spare. Still, comparing these two size tires, the differences are less than 3% and the sidewall is taller on the spare. Driving a distance on it would not be a problem for me. Again that’s my opinion.
PS… the different tire/spare combo was present on my 2003 Duramax. At trade in with 298K miles, the spare never touched the ground. It was replaced around 125K.

 

[JKellerJr]

You could be on the road and may have to drive hundreds of miles on a weekend to get a tire repaired .

That would not be an issue with the combo you have.

The sales manager agreed with me that they should be the same size. He said that is how GM does it with smaller size. He told me to contact Chevrolet customer care, which I did. They opened a case and will get back to me.

Yep, That sounds like a typical dealer response.

I will keep the board updated on outcome

I would guess the biggest issue is going to be is that they don't have steel 20" wheels so the only way to make it happen would be to give you one of the aluminum fancy wheels. I will say when we had an issue with GM before that went to the "case" stage they were fairly accommodating. So maybe they'll work something out.

Had a 2016 Duramax that was out of factory warranty but still under an extended warranty. It had issues that required a new computer(they had none available for the foreseeable future) and fuel pump issues, luckily not a full blow up (CP4). We found a company, I think in Texas, that sold reconditioned computers. We bought it and the dealer installed it. They didn't reimburse us directly for the computer which was like $600 and change if I remember correctly, but they did give us several thousand dollars (6K I think) to use towards a new GM product good for like 3 years for the inconvenience.

 

[RV2600RB]

I still believe they should be the same size tire

It’s not the wheel diameter that matters. It’s the tire diameter. As long as the tire diameters match, you could have a 15” wheel and a 20” wheel. The truck doesn’t know the difference. Although having a spare with the same size wheel is nice, it’s not necessary.

 

[jleonard]

FYI my 21 Ram is the same. 20 inch rims on the truck, 18 inch spare. But at least its a real tire.

 

[CedarCreekWoody]

I understand it is even more critical they be identical size if your truck is four wheel drive.

 

[Riverbug]

I understand it is even more critical they be identical size if your truck is four wheel drive.

True. But it doesn't change what's been mentioned here. A 4WD truck with 20's still comes with an 18" rim with higher profile spare. They are very close in overall size.

 

[RV2600RB]

Yup^^^^

 

[JustDucky]

I have a 2021 2500HD Duramax. It came with the 18" spare. I'm a full time RVer and it can take me days (and miles) before I can replace a flat tire due to my location so I wanted a matching aluminum mag wheel and bought one on eBay for a lot less money than new. When a dealer sells a truck and the new owner wants a set of different rims, the dealer takes the new rims off and installs the owners preferred set. The dealer can't sell the original mag wheels as new, so they are considered "used" and sell at a cheaper price. I believe the term they use is "one off rim", or something like that. At least that's the story I was told. In any case you can save money and the 20 inch tire and rim fit in the same space as the original 18" spare. However, it is a bit heavier.

 

[Jerry Davis]

It’s not the wheel diameter that matters. It’s the tire diameter. As long as the tire diameters match, you could have a 15” wheel and a 20” wheel. The truck doesn’t know the difference. Although having a spare with the same size wheel is nice, it’s not necessary.

Old school here, should be same tire as on truck. Also, the 18-inch spare is a Michele , different tread patterns from Goodyear. Always was told to match radial tires

 

[RV2600RB]

Old school here, should be same tire as on truck. Also, the 18-inch spare is a Michele , different tread patterns from Goodyear. Always was told to match radial tires

Matching tires isn’t necessary with radials. Bias ply matching is a good idea. I’ve run 3 of the same tires with 1 of a different brand and can’t tell the difference. All the tires don’t have to be the same manufacturer, just the same overall diameter.
YMMV