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Max spare tire size

kylant

By kylant
in 2020-2026 Silverado HD & Sierra HD

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kylant Enthusiast

kylant

Posted
Posted

Hey all,
I have searched, but don't find an answer. what is the max size tire that will fit in the spare location? will a 285/75-18 (35") fit up there? I just ordered a set in that size and would like a matching spare.

Another JR Senior Enthusiast

Another JR

Posted
Posted

It would be close. I have the stock Michelin 275/70-18 tires and I’ve had my spare out to do some wiring.  As I was restowing it, I remember I was able to shift it around about an inch, meaning there seemed to be room for about an inch more of tire diameter. I don’t remember what was limiting the movement. 

kylant Enthusiast

kylant

Posted
  • Author
Posted (edited)

i will have to measure. for some reason my spare is the 275/70-18, but my factory tires are 275/65-20, about an inch difference??

Edited by kylant
Another JR Senior Enthusiast

Another JR

Posted
Posted

Yes, the tire calculators say there is about 3/4 inch difference in diameter between the standard 18 and optional 20 inch tires. Your new tire size is maybe another 3/4 bigger. 
 

If you unlock your spare and crank it down just to the point where you can shift it around, you’ll be able to move it and judge how much additional room there is. 

  • 4 weeks later...
Hagar68 Enthusiast

Hagar68

Posted
Posted

a little off the OP, but I did this calculation last night of my 18 spare vs 20 tires and the 3/4 difference.   That sure seems like a lot of difference for the rear differential.  Stunning they would do this on purpose.

 

I think a full size spare will fit.  Going to try it when I rotate next week.

Another JR Senior Enthusiast

Another JR

Posted
Posted
17 hours ago, Hagar68 said:

a little off the OP, but I did this calculation last night of my 18 spare vs 20 tires and the 3/4 difference.   That sure seems like a lot of difference for the rear differential.  Stunning they would do this on purpose.

 

I think a full size spare will fit.  Going to try it when I rotate next week.

I think previous discussions concluded that the speedometer calculations were compensated for the 18s versus 20 inch optional wheels/tires difference depending in which option you have. My speedometer (really odometer) seemed dead on based on one of those surveyed 5 mile check stretches we have in WA. I have the standards 18s on the SLT. 
 

As you say, the differential is the same for both options, so the wheel/tire option does make a slight difference in miles per engine rotation. 

KARNUT Senior Enthusiast

KARNUT

Posted
Posted

20 years ago I considered replacing my spare with a matching tire and wheel for rotation. Discount tire recommended against that. I realized at that time I haven’t had a flat ever. I even worked off road. I always bought better tires for the application, the best I can find. I have had slow leaks never a blow out. At the risk of jinxing myself, I never had a flat. I do carry fix a flat on trips. 

Another JR Senior Enthusiast

Another JR

Posted
Posted
47 minutes ago, KARNUT said:

20 years ago I considered replacing my spare with a matching tire and wheel for rotation. Discount tire recommended against that. I realized at that time I haven’t had a flat ever. I even worked off road. I always bought better tires for the application, the best I can find. I have had slow leaks never a blow out. At the risk of jinxing myself, I never had a flat. I do carry fix a flat on trips. 

I agree for normal road driving. My experience is similar. The last blowout I had (and the last time I had to use a spare) was literally about 1986. The OP’s tire size is close enough I wouldn’t worry about it for a short diversion to get service. 

  • Like 1
  • 3 months later...
  • 1 month later...
Another JR Senior Enthusiast

Another JR

Posted
Posted

I know this thread is a few months old, but someone may benefit from the answer in the future.
 

I finally remembered to look at the spare clearance when I crawled under to disconnect my camper camera.  I have the SLT SRW stock michelin 275/70-18 spare, and it has about an inch clearance to the exhaust heat shield, and just under an inch clearance on the opposite side from where it would touch a frame cross member that angles down. So the 3/4 inch larger diameter full size spare for the optional 20 inch wheels and tires should fit with enough clearance that the tire can still be 1/2” away from the heat shield. 

  • 4 weeks later...
schrutemanager New Member

schrutemanager

Posted
Posted

When I had my 2017 Silverado, I had a full size spare. I had 20’s with 35’s. It fit perfectly underneath. The only thing I had to use was a hub centric ring for the spare tire hoist. 

  • 3 months later...
s98anderson New Member

s98anderson

Posted
Posted

i have a 2020 Yukon XL Denali and I have 20" wheels all around.  I am about to install the Brembo performance front brakes that will not allow for the 18" spare tire to be used up front.  If you have a front tire flat, you have to remove a rear tire, install the spare in the rear, then install the 20" rear tire up front.  I'd really like to just put a used 20" wheel with a beater tire back there and call it good.  Anyone have this problem and will my solution work?

  • 9 months later...
ozmt New Member

ozmt

Posted
Posted
On 7/17/2023 at 12:17 PM, s98anderson said:

i have a 2020 Yukon XL Denali and I have 20" wheels all around.  I am about to install the Brembo performance front brakes that will not allow for the 18" spare tire to be used up front.  If you have a front tire flat, you have to remove a rear tire, install the spare in the rear, then install the 20" rear tire up front.  I'd really like to just put a used 20" wheel with a beater tire back there and call it good.  Anyone have this problem and will my solution work?

 

ozmt New Member

ozmt

Posted
Posted (edited)

I have a new 2024 Sierra ultimate with the brembo brake and 22"wheels. How stupid is it that they ship this out from the factory with a spare that didn't fit! I want to buy a set of 20's for winter tires and keep one under for a spare. Hope it fits under the bed

Edited by ozmt
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