Mismatched spare (1 Viewer)

[RangerDownUnder]

I've found a few other posts about mismatched spare tires but none with the sizes I have so please bear with me through this.

I bought my 105 series about 3 years ago and it's due for new tires. Really it only needs two new tires but I'm replacing all four so they all have matching tread and will last longer with the rotation. The tires that are currently on the rig are 275/70R16 and I'm replacing them with the same size. But it got me thinking that I have never used my spare beyond making sure the pressure was ok so I pulled it out to take a look and it turns out that is 7.50R16C. It sounds like those two sizes are very close in diameter but could there be any consequences if I end up getting a puncture and driving on the larger spare for a long distance? Logic also tells me that if I do need to do that, I should put the 7.50R16C tire in the front and avoid 4WD/locking the hubs, right?

Or should I just get the tire place to pick the best of the worn tires and put it on the spare rim? Would a 275/70R16 tire fit underneath?
Ideally I would just get a brand new spare tire of the same size and do a 5-wheel rotation but I live in regional South Australia and buying four new tires is already stretching my budget so I'm trying not to have to drop an additional $320 for a fifth if I can.

 

[neckbone]

The 275/70 should fit fine underneath. I had a 285/75/16 under my LX for a while. I'm not sure what the actual size difference between those sizes is so I can't answer that question.

 

[Bisho]

I recently replaced my spare because the existing one was 15 years old and the sidewall was practically warn through from riding under the truck (I've only had the truck a few months). Make sure that older spare is road worthy enough to do you some good if you need it.

 

[BnvS]

The 275/70 should fit fine underneath. I had a 285/75/16 under my LX for a while. I'm not sure what the actual size difference between those sizes is so I can't answer that question.

Here's how they compare

 

[gatormark91]

I've found a few other posts about mismatched spare tires but none with the sizes I have so please bear with me through this.

I bought my 105 series about 3 years ago and it's due for new tires. Really it only needs two new tires but I'm replacing all four so they all have matching tread and will last longer with the rotation. The tires that are currently on the rig are 275/70R16 and I'm replacing them with the same size. But it got me thinking that I have never used my spare beyond making sure the pressure was ok so I pulled it out to take a look and it turns out that is 7.50R16C. It sounds like those two sizes are very close in diameter but could there be any consequences if I end up getting a puncture and driving on the larger spare for a long distance? Logic also tells me that if I do need to do that, I should put the 7.50R16C tire in the front and avoid 4WD/locking the hubs, right?

Or should I just get the tire place to pick the best of the worn tires and put it on the spare rim? Would a 275/70R16 tire fit underneath?
Ideally I would just get a brand new spare tire of the same size and do a 5-wheel rotation but I live in regional South Australia and buying four new tires is already stretching my budget so I'm trying not to have to drop an additional $320 for a fifth if I can.

Nothing wrong with that spare as long as you keep it in 2WD.

 

[wvrx]

I run a mis matched spare as well (315/75/16 vs 275/75/17) with the thought that this would be at most a 50-mile patch until I get to a place to get a new tire. Probably just fine unless you keep the center diff locked and do long distance trips away from civilization

 

[BnvS]

Nothing wrong with that spare as long as you keep it in 2WD.

LOL how do you keep the Land Cruiser in 2wd?

 

[Bisho]

LOL how do you keep the Land Cruiser in 2wd?

He’s driving a 105. Lockout hubs.

 

[AlpineAccess]

I think there are many positives to a full size spare in addition to stretching the full sets serviceable life by rotating it in.

Every 5k the tire gets checked. If you get a flat you can drop your punctured tire at a shop for repair and not have to leave your vehicle. You don't have to go for a repair if you get a flat and are on a long trip - swap and drive to your destination and get it fixed.

Running mismatched tires on the same axle is what causes issues, or mismatched axles on an engaged transfer case, for an extended period of time on a high traction surface. If it's short periods, just run the mismatch. If you're concerned you can always air up the smaller diameter tire and air down the oversize slightly to match a little better.