I have just recently had a blowout on my 93 f150 4x4 on the front driver side and it cant be plugged. Just today i came across 2 32x11.5R15. The tires i have on it now are 31x10.5R15. What im wondering is will it be ok if i mix the two sizes? What im thinking about is putting the 32's on the back and the 31's on the front. It will just be temporary for maybe about a month till i can afford to buy a new set. Will doing this effect the 4 wheel drive?

 

You may have problems in 4WD unless you are on very, very loose surfaces.
It's not like an AWD car. There's no differential between the front and rear driveshafts so when the tires rotate, they are going to try to travel different distances for the same input RPM. That gives you a lot of "windup" in the drivetrain.

 

It wont matter too much (at all) if you have two wheel drive. If you have four wheel drive and you plan on using it, I wouldn't do it....

 

shouldnt be done on a 4x4. all tires turn at the same speed and must be the same size

 

You can do it as long as you don't engage 4x4. If you do engage 4x4 with the different size tires you will end up doing more damage than the cost of 1 new tire to replace the blow out.

 

Right now where i live we have been getting quite a bit of snow. I wonder if it would be ok to use the 4 wheel drive only when i really need it. Like when i need to pull a hill in the snow and its gonna be real slick, then disengage it?

 

Not a good idea. If the snow is loose packed enough to not break things in the drivetrain then you'll have the tires spinning at different contact speeds which makes the truck very easy to switch ends.

 

If you're gonna run 2 different sizes do NOT put it in 4 wheel drive unless you're on NOTHING but ice. You'll have at least $1000 in damages (give or take) when you could have went out and got a new tire for $125-$200.
Someone was telling me one time a guy had 2 tires on the front of his truck one size smaller than the rear and it something broke (can't remember what it was) but it cost him a couple grand to get it fixed.

 

I just busted the front drive shaft and put a hole in the Tcase on my F250 a few weeks ago. Cost me about 400 for a new shaft and if they hadn't been able to patch the case it would've been about 1.3k for a new ford transfer case without install. And that was just from old age and wear.

If anything were going to bind up it would be either the shaft or Tcase

 

Jump onto Craigs list and put your tire size in- I'll bet theres a dozen used tires out there in and around your neighborhood for short money to get you through...

 

Ok, thanks for all the replys. I think ill either find a 31 to match the one that blew, or find two more 32's that match the ones that i already bought. As much snow as we've had i dont wanna be left without 4x4.

 

Go actually measure them and I bet only being within less than a 1/2 inch difference anyway.

Sure if you lock it in a tight turn on dry pavement hooked to a bigrig you might pop a ujoint, but that prolly would happen anyway.

A slightly little smaller tire up front will have it spin a hair faster and help pull through messy stuff.

Done on tractors and mud trucks all the time with wilder differing gearset ratios.

I don't see 32 to a 31 being an issue as I've had in the past run 235/75s (= about 30) up front and 31 M/Ts in the back no problems or catastrophic failures.

Adrianspeeder

 

That's exactly backwards. Both are going to be spinning at exactly the same RPM but the smaller front tire is turning at 655 revs/mile where the rear is turning at 677 revs per mile. That means the rear end of the truck is going to be trying to travel about 3.3% faster than the front. Even if that isn't enough difference to bust something (which it probably is) it's enough difference to make the rear come around with little or no warning.