Spare tire size (2 Viewers)

[W Powell]

Quick question - we are taking our 100 to Baja for a few weeks and I am trying to prep it accordingly. Truck has 240k on the clock so its no spring chicken. I just purchased new tires that are not the same size as the spare. Can you run the spare if it is a different size?

Also any advice as to parts or spares I might consider for the trip? At this point I plan to take a tow rope and and a sun hat as my cruiser has always been bulletproof but you never know right...?

Dealer said I have a wheel bearing going out so I might take that on myself prior

Thanks in advance

 

[geanes]

Overall diameter is the concern. You can run a 16" spare tire on a truck with 18" wheels as long as the overall diameter with the tire is very, very close. I have 275/70/18 KO2 and ran temporarily my old 285/75/16 spare. They are both effectively 33" overall with less than a 1" rollout difference. I could have used that spare over short distances without stressing the diffs too much in order to get to safety. But, that would be the extent of the spares use to me. I now have all 5 tires identical.

 

[Slashzero]

Damnit... I was going to post the same question later today. I bought 4 Conti TerrainContacts in 275/65r18, and was thinking about the spare this morning (which is an original size Dunlop 275/60r18).

Looks like I will be buying one more Conti and replacing my spare, which still looks brand new.

How many miles of driving with a slightly smaller diameter tire would it take to cause any serious or permanent damage?

 

[Spike555]

You guys will be fine with the odd sided spare, just don't think you can throw it on and then drive for 6 years with it.
It is a SPARE tire, it is meant to get you to safety. So don't worry about it, IF you get a flat, throw it on, drive to the nearest tire shop and get your flat fixed and put the spare back where it belongs.

 

[Slashzero]

You guys will be fine with the odd sided spare, just don't think you can throw it on and then drive for 6 years with it.
It is a SPARE tire, it is meant to get you to safety. So don't worry about it, IF you get a flat, throw it on, drive to the nearest tire shop and get your flat fixed and put the spare back where it belongs.

Thanks for your reply!

 

[jLB]

You guys will be fine with the odd sided spare, just don't think you can throw it on and then drive for 6 years with it.
It is a SPARE tire, it is meant to get you to safety. So don't worry about it, IF you get a flat, throw it on, drive to the nearest tire shop and get your flat fixed and put the spare back where it belongs.

While I don't disagree that your approach can work. Around town, it's probably a sound approach, but it would still bother the inner engineer in me, on a full time 4wd vehicle w/ ATRAC/VSC. If I were in the OP's shoes ( "taking our 100 to Baja for a few weeks" ) I'd have a strong preference for carrying a matched spare.

One of the nice features of our vehicles is that they come with a matched 5th wheel and enough space for a full sized spare (up to ~33"). Why would I want to reduce its functionality to the equivalent of a "space saver" spare tire?

If a tire was to take damage while traveling (to/through a remote area):

If it's repairable, your unmatched "spare" approach works just fine. I can "plug" the bad tire, or use the mismatched "spare" to drive someplace that can repair the tire for me.

If it's not repairable, and I have to purchase a tire. What happens if the make/model/size tire, that I am using, is not readily available? If I have a matching spare I can replace the bad tire with a close match, and adopt your mismatched "spare" approach until I can find a suitable replacement spare.​

 

[Spike555]

While I don't disagree that your approach can work. Around town, it's probably a sound approach, but it would still bother the inner engineer in me, on a full time 4wd vehicle w/ ATRAC/VSC. If I were in the OP's shoes ( "taking our 100 to Baja for a few weeks" ) I'd have a strong preference for carrying a matched spare.

One of the nice features of our vehicles is that they come with a matched 5th wheel and enough space for a full sized spare (up to ~33"). Why would I want to reduce its functionality to the equivalent of a "space saver" spare tire?

If a tire was to take damage while traveling (to/through a remote area):

If it's repairable, your unmatched "spare" approach works just fine. I can "plug" the bad tire, or use the mismatched "spare" to drive someplace that can repair the tire for me.

If it's not repairable, and I have to purchase a tire. What happens if the make/model/size tire, that I am using, is not readily available? If I have a matching spare I can replace the bad tire with a close match, and adopt your mismatched "spare" approach until I can find a suitable replacement spare.​

I understand what you are saying and I agree to a point, the checking account would be the final decider for me. Do I have the money for a extra $200 tire that the odds are in the favor of me never ever using?
If I were that worried about it I'd go to a junk yard and buy a used tire of the correct diameter.

I respect engineers and understand where they're coming from, you guys always want perfect at whatever the cost.

I'm in transportation, the profit margins are very small, we are really good at playing the odds and taking chances on "what if's" and probabilities to save a few bucks.

The OP can do whatever he wants, he asked for opinions and we all agree that we all have them.

 

[geanes]

My solution was to buy a gently used 275/70/18 tire off Craigslist so I had a "matching" spare for the size....even though it's a TerraGrappler and not a KO2. One thing to consider, and it's mentioned above, is availability of a given replacement size when in more remote locations. One reason I have decided to stick with 275/70/18 and not more up to 295/70/18 is that the former is way more readily available whereas the latter is very limited (Discount Tire only carries 4 in that size). I figure I'll stick with the more prevalent sizes and avoid the "exotics".

Anyway, when I get my replacements someday, I'll do all 5 matching and then go with a 5-wheel rotation vs a 4 so that I have even wear across all tires and can, potentially, get more time between replacements.

As Spike mentions above, I don't think running a mismatched tire will result in damage as long as it's used, well, sparingly. Basically, get to the nearest safe location and replace with a correct tire size. I wouldn't dare drive 900 miles home from Colorado on the highway on a mismatched tire size. But, I would drive 60 miles to a tire shop. Albeit, slowly to minimize any potential damage.

 

[jLB]

I respect engineers and understand where they're coming from, you guys always want perfect at whatever the cost.

I'm in transportation, the profit margins are very small, we are really good at playing the odds and taking chances on "what if's" and probabilities to save a few bucks.

I understand and respect your viewpoint, "~$200 now" vs. "likelihood of never having to use it."

From my perspective, it's not so much about being "perfect at whatever the cost", as it is "what happens when Murphy's law rears its ugly head". What's "the cost of burning a day chasing down a tire, while I'm traveling cross country" vs. "the cost of carrying a matched spare (~$200)".

 

[TxAggieLC]

How many people are running a 295/70/18 tire in the stock spare location? I really want to jump up to that size but worry that a spare wont fit with the hitch left in place. Having a full sized spare is a must considering the long road trips we go on.

 

[geanes]

How many people are running a 295/70/18 tire in the stock spare location? I really want to jump up to that size but worry that a spare wont fit with the hitch left in place. Having a full sized spare is a must considering the long road trips we go on.

I run 275/70/18 (33.2") KO2 and it BARELY fit in the stock location. I don't see how a 34"+ tire (295/70/18) could possibly fit.

 

[TxAggieLC]

I agree that the 1 inch difference in tire size (275 vs 295) would likely make it impossible to get into the spare location. Just curious if there are any real world experiences. I know some have dropped the tow hitch and made it work, but I dont want to do that. I'd rather try to store the tire deflated and inflate it in the event its actually needed. I'll be doing a 5 tire rotation every 5-7k miles anyway so I dont worry much about the tire being deflated, just not sure it will fit even that way!

 

[geanes]

I agree that the 1 inch difference in tire size (275 vs 295) would likely make it impossible to get into the spare location. Just curious if there are any real world experiences. I know some have dropped the tow hitch and made it work, but I dont want to do that. I'd rather try to store the tire deflated and inflate it in the event its actually needed. I'll be doing a 5 tire rotation every 5-7k miles anyway so I dont worry much about the tire being deflated, just not sure it will fit even that way!

If you're using E-Rated tires (which I assume you would be), the sidewall will not want to flex too much without significant force. I would think it might work. But, I'd worry about the tire staying in a flattened state (not round) developing a "hop". Probably irrational, but a thought I have nonetheless.

Another thing to consider would be to simply stow a tire repair kit ($40 or less) and a compressor (Viair 88p is what I use) and not carry a spare. I would think the greatest potential for a flat tire would be a nail or screw in the tire vs a complete blow-out or sidewall tear. I got a screw in one of my previous Nitto TerraGrapplers once. I found it easier to simply plug the tire using my repair kit and reinflate. I was able to make it all the way home (Austin, TX) from Trinidad, CO that way with no issue.

 

[KraziAzn]

You shouldn't run a different size spare. But you can if you want.

At least keep the spare's diameter the same as your other tires. Honestly, I recommend investing in 5 matching tires and do a 5 tire rotation when it is needed.

 

[geanes]

You shouldn't run a different size spare. But you can if you want.

At least keep the spare's diameter the same as your other tires. Honestly, I recommend investing in 5 matching tires and do a 5 tire rotation when it is needed.

I definitely would NEVER run a different size spare. AWD/4WD systems absolutely require same diameter at all 4 corners. I guess you could run a different size off-road to get off a trail since you're not really at any high speed. But, on the road, you'd be doing damage to the differential I'd think.

I run the same size tires on my trailer as are on my LX. This effectively means I have up to 4 full-size spares when I tow the trailer (1 spare on the rear swingout of the LX, 2 on the trailer axles and 1 on the tongue platform of the trailer). Not really looking forward to the upcoming bill at Discount Tire when I buy 8 tires

 

[trdcorolla]

I definitely would NEVER run a different size spare. AWD/4WD systems absolutely require same diameter at all 4 corners. I guess you could run a different size off-road to get off a trail since you're not really at any high speed. But, on the road, you'd be doing damage to the differential I'd think.

I run the same size tires on my trailer as are on my LX. This effectively means I have up to 4 full-size spares when I tow the trailer (1 spare on the rear swingout of the LX, 2 on the trailer axles and 1 on the tongue platform of the trailer). Not really looking forward to the upcoming bill at Discount Tire when I buy 8 tires

Don't change tire sizes!

 

[geanes]

Don't change tire sizes!

I don't and I wouldn't unless it was the ONLY option to get off a mountain/trail to civilization. I carry a repair kit and multiple same sized spares when I go off-road, so the odds I would ever run into a situation where I had to use different size would be practically zero.

I agree with you....different size spare is a no-no in all but the absolute most dire of off-road circumstances....i.e. if I were on the White Rim Trail and had no usable spares left and another vehicle comes along with a usable spare (matching bolt pattern), but in a different size...I'd borrow it to get to pavement.

 

[TxAggieLC]

If you're using E-Rated tires (which I assume you would be), the sidewall will not want to flex too much without significant force. I would think it might work. But, I'd worry about the tire staying in a flattened state (not round) developing a "hop". Probably irrational, but a thought I have nonetheless.

Another thing to consider would be to simply stow a tire repair kit ($40 or less) and a compressor (Viair 88p is what I use) and not carry a spare. I would think the greatest potential for a flat tire would be a nail or screw in the tire vs a complete blow-out or sidewall tear. I got a screw in one of my previous Nitto TerraGrapplers once. I found it easier to simply plug the tire using my repair kit and reinflate. I was able to make it all the way home (Austin, TX) from Trinidad, CO that way with no issue.

Good point about the lack of flex with an E rated tire. I'm looking at the Cooper Discoverer AT3 LTX which is a two ply tire so maybe a little more compliant than a 3 ply, but stiff nonetheless.

Great idea about grabbing a tire kit and carrying an air compressor. I may start off with that option. I'll probably just order 4 tires and see if I can stuff a deflated 295 in the spare location. The thought of the tire developing a hop also crossed my mind but with them being rotated at a 5-7k interval, I doubt its too much of a concern.

If only I could just bite the bullet and get a rear bumper with a swing out....

 

[geanes]

Good point about the lack of flex with an E rated tire. I'm looking at the Cooper Discoverer AT3 LTX which is a two ply tire so maybe a little more compliant than a 3 ply, but stiff nonetheless.

Great idea about grabbing a tire kit and carrying an air compressor. I may start off with that option. I'll probably just order 4 tires and see if I can stuff a deflated 295 in the spare location. The thought of the tire developing a hop also crossed my mind but with them being rotated at a 5-7k interval, I doubt its too much of a concern.

If only I could just bite the bullet and get a rear bumper with a swing out....

The AT3 LTX is a great tire by all accounts and solid choice IMO for a mostly daily driven rig that will occasionally go off-road. If you're putting 2400-3000/month like me, you shouldn't have any issue with the possible tire "hop" issue. I'd think that more relevant for those who occasionally drive their rigs like 500-1000/month. A tire repair kit and compressor is an absolute MUST have IMO along with quality tires. You have those 3 things and you can challenge just about any offroad trail with confidence.

As for the rear bumper....well, that opens a whole nother can of worms there. Typically BIG $$$$ and the added hassle of needing to open one or two (if you have 2 swingouts) elements prior to opening the hatch/tailgate. Sure, it makes getting to your spare MUCH easier (especially in rocky, sandy or muddy conditions. But, be prepared for the daily inconvenience if you access your rear cargo area often. I love mine. But, it's definitely a trade off......convenience in once aspect and inconvenience in another. But, I'd rather have easier access to my spare and the ability to carry additional fuel via jerry cans.

 

[TxAggieLC]

The AT3 LTX is a great tire by all accounts and solid choice IMO for a mostly daily driven rig that will occasionally go off-road.

Thats my thinking exactly and glad others agree. The LC will be used mostly for DD and road trips with some occasional mild off-roading. By no means will this thing see any rock crawling or insane articulation. Just need it to handle some South Texas hunting leases and mild trails in Colorado. I think the AT3 LTX will live up to those expectations. That said, if BFG made the KO2 in a 285/70/18 or 295/70/18, thats the tire I would have gone with.

Agree on all fronts regarding the rear bumper. Definitely some trade offs and if it wasnt for this spare tire dilemma, I probably wouldnt give it too much consideration given what I'm using my LC for. Just too much daily inconvenience due to the rig being a family hauler 99% of the time.