Who has actually run a different diameter spare

[wfo9]

Title should have mentioned SLIGHTLY DIFFERENT DIAMETER

I know that having a different diameter tire on the truck is not a good idea for multiple reasons. However, I don't think it is possible to fit an exact match for my tires (34") in the spare location. Plus they are pretty wide, so it would hang down too much. Trying to avoid a swing out or a roof mount.

I was thinking of getting a pizza cutter tire (like the k02 34x10.5) for the spare which would measure 33.5 vs the 34.1 of my MTRs. I'm pretty sure that would fit under the truck and provide decent clearance.

The question is who has actually run slightly mismatched diameters on the road. I think it will be fine off-road, but curious how bad it will freak out all the on road electronics.

I may just need to try it out and see what happens, but my current spare is 32.8" and not sure if I want to invest in another tire...

I carry plugs and on-board air... so the spare is a last resort kind of thing, but I would not go without something.

 

[1engineer]

The vehicle should be able to run a completely new tire and a completely worn tire of the same size at the same time. I would feel comfortable running tires that had that much deviation regardless of their beginning size.

Pretty sure the engineers would have figured out and allowed for putting a brand new spare of the same size on with tires that had 50K miles on them.

 

[BobsTrail]

I would put the spare up front if possible and turn off VSC and Trac until it's fixed.

 

[nb rob]

It's not so much the pouting electronics as the howl of the differential that will really spoil your ride home. I agree with 1Eng - worn sizes of the same nominal dimensions should be fine, and I think that might be the limit of the specification. My friend popped a 265/70/r17 spare on his half ton and insisted that it would be fine for the 100km drive back to town. A few km down the road and the howl was HORRIBLE. He only had [overly worn] 285's on his truck. That's not what I would consider a small difference in diameter.

To be honest, I thought it wouldn't be great for his truck, but I had no idea it was going to sound so bad. He turned the radio up. It was like nails on a chalkboard for me for over an hour. Part of that was because his taste in music sucks.


I've also got my tire patch scout badge. But in the last few years, I've encountered 3/5 holes that couldn't be patched to satisfaction. Full sized-spares are a must for me now. If only as a safety blanket.

 

[wfo9]

I think I would definitely make sure I put the spare up front. That would eliminate any potential strain on the diff. With the ADD in the Toyota's, only the drivers side front axle is spinning the diff when in 2wd.

Off-road, I think diameter could be pretty much be matched with tire pressure alone. I see no issues with .5" delta there.

As far as turning TRAC and VSC off.. I have not done that much, but it seems to still be there, just in a much less aggressive mode.

 

[03_4x4Runner]

Where are you going to put the flat tire if it will not fit in the spare location? Maybe it will fit deflated. As for running the spare possible you could overinflate the smaller tire and underinflate the bigger ones to help equalize the diameter.

 

[jasonv]

most vehicles (cars) don't come with full size spares. you can run a different size, the diffs will handle it up to a certain speed and distance before it starts to affect the lubrication.

i run 275's and my spare is the 265 that came with the truck. not too worried about it but i'm still going to get the tire fixed asap if something happens.

 

[Jeremy556]

My friend popped a 265/70/r17 spare on his half ton and insisted that it would be fine for the 100km drive back to town. A few km down the road and the howl was HORRIBLE. He only had [overly worn] 285's on his truck.

Guessing it had an LSD, G80, or some other traction device. The open diff on the 4runner is not going to care about mismatched wheel speeds.

When I had 285 tires, I ran a 265 spare for a few days while one of the 285s got replaced. Had no issues with VSC, trac, etc. I'm carrying a 285 spare for my current 305s but haven't had to use it, yet.

Since running MTRs I get very few punctures compared to Duratracs, in fact none, yet. I had at least 1, some 2-3 puncture/repairs in every one of my Duratracs.

 

[wfo9]

most vehicles (cars) don't come with full size spares. you can run a different size, the diffs will handle it up to a certain speed and distance before it starts to affect the lubrication.

i run 275's and my spare is the 265 that came with the truck. not too worried about it but i'm still going to get the tire fixed asap if something happens.

I'm not really concerned with the diffs much. Except for when needing to be locked offroad or ATRAC. After all, they are made for dealing with different speed rotations in a turn. However, the 4Runners electronics (ABS, VSC, TRAC....)don't expect there to be a different size tire on the vehicle. And I don't think they can be completely disabled.

I was hoping someone has actually done it.... I dove x00 miles with size X and and Y.... This is what happened.

I'm mainly worried about being thousands of miles from home with a tire that can't be repaired. Since my tires are in short supply... It would probably be impossible to order a replacement in a reasonable time frame.

 

[wfo9]

Guessing it had an LSD, G80, or some other traction device. The open diff on the 4runner is not going to care about mismatched wheel speeds.

When I had 285 tires, I ran a 265 spare for a few days while one of the 285s got replaced. Had no issues with VSC, trac, etc. I'm carrying a 285 spare for my current 305s but haven't had to use it, yet.

Since running MTRs I get very few punctures compared to Duratracs, in fact none, yet. I had at least 1, some 2-3 puncture/repairs in every one of my Duratracs.

Perfect, that was in the info I was looking for. That was also one of the reasons I got the MTRs.

 

[wfo9]

Where are you going to put the flat tire if it will not fit in the spare location? Maybe it will fit deflated. As for running the spare possible you could overinflate the smaller tire and underinflate the bigger ones to help equalize the diameter.

If I did end up with a flat, it would probably need to go inside (if there was room) or on the roof. I carry some straps for that situation.

 

[BlackWorksInc]

The vehicle should be able to run a completely new tire and a completely worn tire of the same size at the same time. I would feel comfortable running tires that had that much deviation regardless of their beginning size.

Pretty sure the engineers would have figured out and allowed for putting a brand new spare of the same size on with tires that had 50K miles on them.

I have to agree with you, but Toyota does make a point to stress that the tires should be close in diameter to each other down to I think 3/32" (if I remember right.) Though I think it's more that they're being conservative in that respect.

 

[03_4x4Runner]

If I did end up with a flat, it would probably need to go inside (if there was room) or on the roof. I carry some straps for that situation.

In my younger days I may have been able to get a tire that size on the roof by myself (probably with damage to the 4runner or a broken window) but not anymore.