99SR5

iTrader: (1)

dirt wont make a difference. its not like a locker where it'll spin easier in the dirt. the smaller tires will turn faster than the larger ones and the difference in speed has to meet somewhere and something has to take the stress of two different driveshafts spinning at different speeds....

dont run 4wd. but if you have to you'll figure out what we're talking about. you can listen to some people but im telling you dont do it

streetlancer

iTrader: (1)

I've been running worn 235/70r15 in the front and new 235/75r15 in the back for a couple of years and have had no problems with 4wd. On top of that the transfercase has 292,xxx original miles with no work to it. Still Rockin!!

az4x4runner

You said earlier you have plenty of customers that have had problems due to this, I assume you work at a shop/dealership?

Nice dude, that's the kind of stuff I like to hear about!

RustBucket

iTrader: (1)

Would a little experimentation answer your question? Drive a little on the pavement in 4WD and see if there's binding? Or just run one tall tire in the back and one in the front and let the diffs make up the slack!

Jay351

You shouldnt ever drive in 4wd in high traction areas anyways. Not a problem.

I had to use 4wd a few times a few winters ago with 4.88's in the back and 4.56's up front..

a 1/2" difference in tire diameter is like splitting hairs.. Tires will change as the tread wears

chubbydude

I would say that as long as you are on slow, low traction roads then it should be fine. On the other hand if you want to use 4wd on winter highways at high speeds, 1/2 inch is a big difference and the life of your drivetrain will be shortened.

jared41

It's not an audi, everything will be fine. Plus it's June so nobody is going to use 4wd on pavement... run it!

Jay351

As long as you follow the main rule as specified by the big ass sticker on your sun visor to NOT use 4wd on high traction surfaces you are fine.

99SR5

iTrader: (1)

yeah i work at a shop... we've gotten in trouble for putting two new tires on an awd car and their entire drivetrain had to be replaced, same thing happened to an F-150 that came in.. point is, dont run 4WD till the tires are all the same

EVERYONE, TRACTION HAS NOTHING TO DO WITH IT. ITS NOT LIKE RUNNING A LOCKER ON THE STREET. ITS THE FACT THAT THE FRONT AND REAR TIRES ARE NOT SPINNING AT THE SAME SPEED.

az4x4runner

Even in the winter here I don't use 4wd unless the roads are covered with snow/ice, in such a situation I would be less concerned about tire size than on dirt, considering the tires ability to slip on snow/ice.

I think you guys have satisfied my paranoia. I definitely know better than to use 4wd on high traction surfaces...

Also, as stated in my original post, I've been running this setup without giving it a second thought since winter 2008... no problems, just got to thinking/worrying and thought I'd get some opinions.

az4x4runner

AWD, from what I understand different size tires can ruin the center diff.

Traction has a lot to do with it in my opinion. I'm sure I would have blown something up had I been running it like this the last year and a half on pavement, but all is well.

I still believe that even turning is more stressful to the drivetrain in 4wd than my 1/2" tire difference. You can hear the back wheels slip to unload the binding when turning. I feel/hear no binding going straight with my mismatched tires.

Stuwy123

iTrader: (1)

Do some burn outs to even 'em up a bit.

Ever heard of the 5 finger discount, BAM you've got new tires!

Teuf

I say run it, and at the same time remove half the oil and A/F, good luck.

myyota85

x2 on the burnout smoke them puppies down just get it on tape......

Jay351

I just got a new set of rims. I plan on throwing the two rims with 29" tires on the back and burning them up! Haha

myyota85

u tube it.....

az4x4runner

I wish my truck could spin M/Ts. I'd have to throw some sand down first.

az4x4runner

That's some good advice! What about the tranny and diffs? I usually just fill both them up with water.

Jay351

Don't worry. Its getting filmed

Jay351

Don't forget the sand and wood chips, that helps too!