Flat tire and Small spare

Well I had some bad luck and got a flat on a gravel road last night. I am running 285s but the spare is only a 265 and of course it happened Saturday night so I am hard pressed to find a tire shop today. The one I did go to said they couldn't fix it. I am going to have new tires on the way and plan to pick up a used 285 tomorrow after work. Should I move the 265 to the front to drive to work or will it be okay running it in the back? I am worried about my diff and have a 40 or so mile round trip

 

Uh yeah, you should have moved a front tire to the back and ran same size tires on your rear.

 

Just curious as to why you upgraded all the tires but didn't increase the spare to the same size??

 

Its actually pretty standard for alot of people. I did the same until I got a flat on a trail alone one night and had to swap front to back with a bottle jack

 

It had the 285s when I bought it. A full size spare was on my short list of parts to acquire. Unfortunately I didn't get it soon enough apparently.

 

Yep I was in the same jam and wasn't thinking when I did it. I'll go move tires around.

 

The rear is an open diff so there is no problem running different tire sizes for a short time.

 

Would severely not advise is it though. Swap your fronts to the back and run mis-sized on the front. Thats how you burn up a dif really fast

 

^^^This unless you plan on engaging the locker if you have one.

 

So a differential that is made to spin at different speeds while turning all the time normally will grenade itself if it thinks there is two different size tires?

 

Depends if its a true open or if its limited slip. And they are designed to run a different speeds when you turn, doing it non stop on the highway is a good way to ruin your third.

 

So how is the front diff better suited to run a different tire than the rear???

 

It's not. Only difference is that it's not under power assuming you're in 2wd. So unless you have manual hubs, your front diff is always spinning too.

 

Well aware the front diff is always spinning. Has anyone put any thought into the fact that different size tires in the front can cause adverse braking? I would rather my truck (though I have a matching spare) not pull or cause the ABS to kick on unnecessarily under emergency braking.

 

That would be my biggest concern, but I'd use the smaller spare just to get down the trail. Or limp to the nearest tire shop.

 

Were talking a difference of 30 revolutions per mile between the 265 and 285. I hardly think that the diff gears are going to be overworked in that case. Is that gonna cause weird steering a breaking? Probably. Would I run this setup on the regular? No. But will it blow the diff? I highly doubt it.

 

Yep! No worse for the diff than driving on a road with curves in it. And living on an island, there are very very few places here where the road is perfectly straight for very long...

 

For those that "think" a different sized tire is going to ruin the differential, think about this.

Small spare tires have been in use for YEARS and I have never seen one take out a differential. As long as you do not abuse it it isn't going to harm or increase wear on anything. Just like the smaller spare tires you should keep the speed down and get it replaced as soon as you can.

I would not move the smaller tire to the front.

 

I couldn't jack it up high enough to move it. So I drove slow yesterday keeping it around 45-50 and made it okay. I picked up a used tire the right size last night to get me by until my STMaxx come in.