A/T P tires in front, Highway LT's in back, any problem?

Mike134 wrote:

JRscooby wrote:
Does nobody remember "snow tires"? Back in the day most people, on most vehicles, ran rear tires that did not match the front for about half the year.
(On my pickups, snow tires in winter, then spring I would name them "Mud Grips")
As for different size F/R. 2 wheel drive, this is not a issue. 4 Wheel drive, can be a problem unless on surfaces you need 4 WD, and tires can slip

X2!! Plus in the early days they always recommended keeping radial tires and bias tires on the same axle, lots of mix and matching back in the old days.

You'll be fine don't listen to the online negative Nellies.

Because vehicles are EXACTLY the same as they were in the 60's and 70's...

First off back then vehicles were almost all rear wheel drive with open differentials. No ABS. No all wheel drive. Heck not even four wheel drive unless you owned a ranch or were a forest ranger.

Of course having different size/type tires front and back is not a concern on a basic RWD vehicle. You could even have grossly different size tires side to side on the front with no ill effects, as there are nothing but dumb wheel bearings up there.

When there is a differential in the mix, then it becomes more important. Differentials 99.999% of the time act like solid axles, with both tires turning at the same rate as long as the tires are the same size in the same state of wear. Things only move back when making turns, and maybe a little bit of back and forth movement going straight down the highway.

When you put different size tires on a differential axle, the spider gears are turning all the time. They're not meant to do that CONSTANTLY, only on turns, and when you get up to highway speeds, things can be whipping around in there pretty violently, leading to excessive wear and early failure of your differential.

Having all four tires the same size and type is most important on an AWD vehicle, as there is a third differential between the front and rear axles.

Beyond that it depends on how your ABS system works. If it compares front and rear rotation rates you might have trouble with the ABS activating, having different size tires front and rear.

Yes, I understand that the P and LT tires may have the same NOMINAL size, but they can be different diameters.

Cast your votes now for silly thread of the week for this beauty!

mkirsch wrote:



Because vehicles are EXACTLY the same as they were in the 60's and 70's...

First off back then vehicles were almost all rear wheel drive with open differentials. No ABS. No all wheel drive. Heck not even four wheel drive unless you owned a ranch or were a forest ranger.

Of course having different size/type tires front and back is not a concern on a basic RWD vehicle.

I think I said 4X4 could be a issue, unless you stay on slick surfaces. A 2 wheel drive pickup is real close to a basic RWD vehicle. If the tires on the back match each other your differential will be quite content, no matter the size of tires on the front.

Beyond that it depends on how your ABS system works. If it compares front and rear rotation rates you might have trouble with the ABS activating, having different size tires front and rear.

Yes, I understand that the P and LT tires may have the same NOMINAL size, but they can be different diameters.

Yes, there is a good chance P and LT tires will be different circumference. But 2 LT tires with different load range will be different height under same load. Bell, back in the '70s a stack of brand new, same brand truck tires same size 11:00 22.5s good vary over a inch in circumference.

Well folks, i certainly learned a lot in this conversation.

Turns out it's all moot, the shop just called to tell me the slow leak on one of my GOOD front tires is a small sidewall puncture so i ordered two more Michelins. - PAINFUL

hertfordnc wrote:
Well folks, i certainly learned a lot in this conversation.

Turns out it's all moot, the shop just called to tell me the slow leak on one of my GOOD front tires is a small sidewall puncture so i ordered two more Michelins. - PAINFUL

Well, that's good you have it figured out.
But don't feel bad about 2 of them, I have to order 6 Michelins!

BobsYourUncle wrote:

hertfordnc wrote:
Well folks, i certainly learned a lot in this conversation.

Turns out it's all moot, the shop just called to tell me the slow leak on one of my GOOD front tires is a small sidewall puncture so i ordered two more Michelins. - PAINFUL

Well, that's good you have it figured out.
But don't feel bad about 2 of them, I have to order 6 Michelins!

The painful part is paying good money for Michelins....
Not sure about y'alls parts, but if getting "stock" size pavement pounder tires, especially on an old truck that may have 16" or 17" wheels, generally you can find a set of new or good tread newer takeoff wheels and tires combo for less than a set of new new tires.

If I'm just looking for new rubber that's generally what I'll do even if it means selling the old rims and tires. Someone will always buy a complete set, although if you have 2 mismatches and a puncture, the whole mess really aint worth shizz unless the wheels are real nice.

JRscooby wrote:

mkirsch wrote:



Because vehicles are EXACTLY the same as they were in the 60's and 70's...

First off back then vehicles were almost all rear wheel drive with open differentials. No ABS. No all wheel drive. Heck not even four wheel drive unless you owned a ranch or were a forest ranger.

Of course having different size/type tires front and back is not a concern on a basic RWD vehicle.

I think I said 4X4 could be a issue, unless you stay on slick surfaces. A 2 wheel drive pickup is real close to a basic RWD vehicle. If the tires on the back match each other your differential will be quite content, no matter the size of tires on the front.

Beyond that it depends on how your ABS system works. If it compares front and rear rotation rates you might have trouble with the ABS activating, having different size tires front and rear.

Yes, I understand that the P and LT tires may have the same NOMINAL size, but they can be different diameters.

Yes, there is a good chance P and LT tires will be different circumference. But 2 LT tires with different load range will be different height under same load. Bell, back in the '70s a stack of brand new, same brand truck tires same size 11:00 22.5s good vary over a inch in circumference.

The implication is because we did it "all the time" in the 60's and 70's, that it's not a problem on any modern vehicle, and that is incorrect.

It’s not a problem at all unless any of the tires aren’t suited for the load or it’s going to be in awd or 4wd with different diameters.
ABS won’t even be an issue in my experience although grossly different diameters may be.
We put 1 or 2 new tires on our work trucks all the time. Some of them run around with the spare on 1 wheel almost perpetually it seems. And not likely same tread and likely not the exact same diameter (diff tread/brand/wear).

Y’all make mountains out of mole hills here…

mkirsch wrote:



The implication is because we did it "all the time" in the 60's and 70's, that it's not a problem on any modern vehicle, and that is incorrect.

I bet with any brand new 4X2 pickup adult driven, with Ps on the front, LTs on the rear will have no handling issues. Now we got to share the road with the guys that think need tires so big they won't fit under the body. They do affect handling.

JRscooby wrote:

mkirsch wrote:



The implication is because we did it "all the time" in the 60's and 70's, that it's not a problem on any modern vehicle, and that is incorrect.

I bet with any brand new 4X2 pickup adult driven, with Ps on the front, LTs on the rear will have no handling issues. Now we got to share the road with the guys that think need tires so big they won't fit under the body. They do affect handling.

Handling is not the problem. Mechanics is the problem.

On a 4x2 the main thing you have to worry about is your ABS. When your front tires are going at a different speed than your rears, will the ABS kick on at 5MPH, because it thinks one or the other is skidding? If the difference is small enough, maybe not, but taken to the extreme, you could very easily have trouble.