Spare Tire

Vintagemud · August 12, 2007

I was washing my 08 silverado LTZ and I noticed that the spare wheel and tire are a diffrent size and type.While I ordered it with an 20" tire and wheel upgrade it came with goodyear eagle LS2 tires and the 5 spoke GM wheels. However the spare is a 17 inch wheel with a goodyear wrangler tire on it is this normal ?Does anyone else have a truck with this option is your spare a 20" ? I can see them just using a black steel wheel for the spare I would think that should at least be the same size. And I know when you order the 20" wheel package it states that the spare wheel will not cosmetically match the other wheels but it says nothing about size.

zozmanGMC · August 13, 2007

I was washing my 08 silverado LTZ and I noticed that the spare wheel and tire are a diffrent size and type. While I ordered it with an 20" tire and wheel upgrade it came with goodyear eagle LS2 tires and the 5 spoke GM wheels. However the spare is a 17 inch wheel with a goodyear wrangler tire on it is this normal? Does anyone else have a truck with this option is your spare a 20" ? I can see them just using a black steel wheel for the spare I would think that should at least be the same size. And I know when you order the 20" wheel package it states that the spare wheel will not cosmetically match the other wheels but it says nothing about size.

Having a spare tire that is different in manufacture and size may occur on your vehicle. My 2007 GMC Sierra came with 265/70/17 machined aluminum wheels (RPO N88) along with a similar size steel spare wheel/tire. I changed them over to the OEM 275/55/20 P60 wheels as you can see in the picture below but I also bought a similar aluminum spare wheel and similar sized tire. I have the same size wheels and same tire manufacturer on all five of my wheels. I want to mention that if you compare my OEM 17-inch wheels/tires with the 20-inch wheels/tires, they are very close in diameter (1% error). I think you are OK diameter-wize to keep your 17-inch spare to use with your 20-inch road tires. If I were you, I'd change it out to have five matched wheels and tires. You, obviously, do not necessarily need that because you do not have a 4x4. Take a look at the conflicting information which is printed in my owner's manual:

Your vehicle may or may not have a spare tire depending on the model. (p. 596).

NOTICE: If your vehicle has four-wheel drive and the different size spare tire is installed on your vehicle, do not drive in four-wheel drive until you can have your flat tire repaired and/or replaced. You could damage your vehicle, and the repair costs would not be covered by your warranty.Never use four-wheel drive when the different size spare tire is installed on your vehicle. (p. 597)

Your vehicle may have a different sized spare tire than the road tires which were installed on your vehicle. This spare tire was developed for use on your vehicle, so it's allright to drive on it. If your vehicle has four-wheel drive and the different size spare is installed, keep the vehicle in two-wheel drive. (p. 597)

Do not mix tires and wheels of different sizes, because they will not fit. Keep your spare tire and wheel together. If your vehicle has a spare tire that does not match your road tires and wheels in size, do not include the spare in the tire rotation. (p. 597)

CAUTION: Mixing tires could cause you to lose control while driving. If you mix tires of different sizes, brands, or types (radials or bias-belted brands), the vehicle may not handle properly and you could have a crash. Using tires of different sizes, brands or types may also cause damage to your vehicle. Be sure to use the same size, brand and type on all wheels...When new, your vehicle included a spare tire and wheel assembly with a similar overall diameter as your vehicle's road tires and wheels, so it's all right to drive on it. Because this spare was developed for use on your vehicle, it will not affect vehicle handling. (p. 569)

Welcome to GM Tire Economics 101.

zoz

BrandonS · August 13, 2007

I was washing my 08 silverado LTZ and I noticed that the spare wheel and tire are a diffrent size and type.While I ordered it with an 20" tire and wheel upgrade it came with goodyear eagle LS2 tires and the 5 spoke GM wheels. However the spare is a 17 inch wheel with a goodyear wrangler tire on it is this normal ?Does anyone else have a truck with this option is your spare a 20" ? I can see them just using a black steel wheel for the spare I would think that should at least be the same size. And I know when you order the 20" wheel package it states that the spare wheel will not cosmetically match the other wheels but it says nothing about size.

We bout an LT1 and paid extra for the wheels to be put on. Ours has the wheel as you mentioned as well for the spare. We were told that the 20" combination tire/wheel will not fit in the stock spare tire well. That could have been a lie, but I'm not going to try to fit one up there since I don't have an extra one.

I'm not sure how much they are off, but would it hurt the rear-end with completely different sizes because if you put it up front it sure would pull to one side really bad.

zozmanGMC · August 13, 2007

...We were told that the 20" combination tire/wheel will not fit in the stock spare tire well. That could have been a lie, but I'm not going to try to fit one up there since I don't have an extra one.

Lie. They lie.

zoz

MS3DALE · August 13, 2007

Heres a bulletin on this.......

Document ID# 1858650

Subject: Info - Spare Tire is a Different Size than Other Tires #02-03-10-001C - (08/28/2006)

Models: 2002-2007 Cadillac Escalade Models

2000-2007 Chevrolet Suburban, Tahoe

2002-2007 Chevrolet Avalanche

1999-2007 Chevrolet Silverado

2001 GMC Sierra C3

2001-2007 GMC Yukon Models

2002-2007 GMC Sierra Denali

1999-2007 GMC Sierra

This bulletin is being revised to include the 18" and 22" Accessory Wheel available through GMSPO and to update the model years. Please discard Corporate Bulletin Number 02-03-10-001B (Section 03 -- Suspension).

This bulletin is being issued to supply additional information concerning the spare tire on the above vehicles. You or your customers may have noticed that the spare tire has a 16-inch diameter steel wheel while the road tires have a 17-inch, 18-inch, 20-inch or 22-inch diameter aluminum wheel. Although the spare tire has a different wheel diameter and may be a different brand, the rolling circumference is nearly identical to the road tires. The size difference will not cause a concern because the spare and the other tires will travel the same distance in one revolution.

This combination of non-matching tires is used most often on full-size trucks. These vehicles use a road tire and wheel combination that may be too large to conveniently fit the storage compartment space of the vehicle. The customer may not be able to easily remove the spare tire/wheel from the storage area because of its size and/or weight. A steel spare wheel, rather than an aluminum one, may be used since the spare is stowed under the vehicle where it is exposed to road and weather elements. A steel wheel is less likely to incur cosmetic damage while in the stowed position for long periods of time.

Please provide this information to your customers. Also, remind your customers of the importance of following the tire maintenance schedule as listed in their Owner Manual. Additional tire care information can be found by visiting www.gmtiresafety.com or contacting GM toll-free at 1-866-522-0505.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Document ID# 1858650

zozmanGMC · August 13, 2007

Document ID# 1858650 ... Spare Tire is a Different Size than Other Tires #02-03-10-001C - (08/28/2006) ...

You or your customers may have noticed that the spare tire has a 16-inch diameter steel wheel while the road tires have a 17-inch, 18-inch, 20-inch or 22-inch diameter aluminum wheel. Although the spare tire has a different wheel diameter and may be a different brand, the rolling circumference is nearly identical to the road tires. The size difference will not cause a concern because the spare and the other tires will travel the same distance in one revolution.

Comment: Correct.

This combination of non-matching tires is used most often on full-size trucks. These vehicles use a road tire and wheel combination that may be too large to conveniently fit the storage compartment space of the vehicle. The customer may not be able to easily remove the spare tire/wheel from the storage area because of its size and/or weight. A steel spare wheel, rather than an aluminum one, may be used since the spare is stowed under the vehicle where it is exposed to road and weather elements. A steel wheel is less likely to incur cosmetic damage while in the stowed position for long periods of time.

Comment: Partially correct. You may not be able to get a 22 or 24-inch spare under your vehicle, that's true. And they weigh a ton. But the 17-18-20-inch wheels fit nicely. Ever look at your steel spare wheel/tire after several years underneath your truck? It's all rusted to hell. You wouldn't want to use it even if you could get it down. I make it a practice to switch out my rusting capable steel wheel to an aluminum one which holds up better under the frame with all the adverse weather conditions here in Illinois. The aluminum wheels are clear-coated, unlike the steel wheel, and resists corrosion much better. GM just doesn't want to give you a fifth aluminum wheel that you paid for when you upgraded your wheel package.

zoz

hotwheels57 · August 13, 2007

I'm sure if you paid extra for a spare 20" spare tire/wheel, any GM dealership would be glad to include one. Whether it fits doesn't really matter if it's what you really want. There is a significant weight difference between a 16"/17" and a 20" wheel/tire though.

I also changed from the Z71 type aluminum wheels/tires in favor of the 20" LTZ aluminum wheels/tires. Personally, I wouldn't want a 20" as a spare. It would be a bear to get up/down if it would even mount in the oem spare space/mount. It would be more visible. It would look like crap pretty quickly from road grime, rock chips, etc in a short time. Come to think of it, I've never even used my spare tire/wheel on any of my vehicles in recent years. I carry a small compressor and plugs to re-inflate a tire (unless the bead is broken) which is sufficient to get me to the nearest tire shop for professional repairs.

Go to this site and enter the 16"/17" and the 20" tire sizes. You'll see they're within a very close % of each other in OD. It'll also tell you the % of speedometer error if you had to run the 16"/17" spare on the truck.

http://www.miata.net/garage/tirecalc.html

Vintagemud · August 13, 2007

well then they should change the ordering info cause it just says the wheel is cosmetically different.Also the bulletin does not say the 2008s .I could see them using a steel wheel under the back for a spare But I think the tire sould be the same size and type as whats on the truck thats what your paying for.

hotwheels57 · August 13, 2007

You seem determined to find "issues" with your GM truck(s)...

Vintagemud · August 13, 2007

You seem determined to find "issues" with your GM truck(s)...

no I love my truck .it Just I was surprized to find the wrong size spare on it

hotwheels57 · August 14, 2007

That's good to hear. Anyway, it's easily rectified if you're determined to do so and willing to deal with any issues related to the larger size.

If you plan to add a catback system at a later date, will the larger OD spare tire/wheel become an issue? You might end up having to remove the spare tire/wheel anyway depending on what system you ultimately decide on. Could you deal with mounting the larger size spare tire/wheel in the bed? That might be an option, especially if you also plan on a bed cover in the future.

Puggy · August 14, 2007

I have 275/55 20" on the ground and a 275/70 17" spare. They only differ by a total of 6 revolutions per mile. I seriously doubt that difference will cause any problems, even with limited slip and AWD. I'm just happy to still have a real tire for a spare.

az'03Silverado · August 14, 2007

It's to encourage you to actually get the tire fixed if it goes flat instead of driving around on the 'doughnut'. Even if you got a 20" spare it would still only ge good for limited use because it's pressed up against the frame and rubbing there for miles and miles and months and months and is really not a permanent solution because it's going to have weak spots and even unbalaned spots due to it being mounted like this. To keep people from using it until it's worn out, they make it ugly.

2004GMC1500CC · August 14, 2007

You seem determined to find "issues" with your GM truck(s)...

no I love my truck .it Just I was surprized to find the wrong size spare on it

It's not "wrong", you just don't like it. The job of the spare is to get you somewhere safe in case you have a failure, repair the failure and go on. Having 5 of the exact same wheels/tires doesn't make it "right". Besides, I don't think that wimpy cable that holds the spare in place could support much more weight than it does.