# Two different tires on 4X4



## PR Fect (Oct 22, 2003)

I just pick up a 1998 Chev 3500 4X4. It has a 8 1/2 foot Boss Pro V. I have plowed snow for 30 some years. Mostly with equipment like end loaders, and large dump trucks. So I am new to the pickup truck plowing. This pickup has LT265/75R16 tires on the front, and two LT285/75R16 tires on the back. My first thought is no good for the drive train when locked up. Does it make that big of difference? If I only go 4 wheel wile plowing, will it hurt? Is there a reason you would want smaller tires on the front? PR


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## grandview (Oct 9, 2005)

Most likely that is what the guy had lying around. If they were 16's and 17's you'll have trouble.


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## Mark13 (Dec 3, 2006)

You want them a whole lot closer in size then that. Some small variations are ok but either switch them all to 285s or all to 265s. That much difference is just asking for broken parts.


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## 91AK250 (Nov 28, 2007)

i can already hear somthing going boom.


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## GSS LLC (Jul 7, 2012)

Larger tires make fewer revolutions in a mile than smaller tires. That makes your transfer case and drive shafts and axles try to spin at different speeds, breaking stuff, match tires ASAP.


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## vintage steel (Nov 15, 2011)

The 285 and 265 refers the the width of the tire. The 285's are wider than the 265's. They are all 75 series tires, and therefore, are all [theoretically] the same heigth and diameter. They should be fine.


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## B&B (Nov 4, 2006)

vintage steel;1490486 said:


> The 285 and 265 refers the the width of the tire. The 285's are wider than the 265's. They are all 75 series tires, and therefore, are all [theoretically] the same heigth and diameter. They should be fine.


 Would you call a height difference of 1.6" theoretically the same? Because that is the difference between 265 and 285 when the aspect ratio remains the same. And 1.6" is too much.


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## got-h2o (Sep 26, 2008)

I'm surprised it moves at all in 4wd. If you don't notice it hopping like crazy in 4wd on dry pavement, chances are 4wd isn't even working


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## got-h2o (Sep 26, 2008)

Uh ya......75 means the height of the sidewall is 75% of the width. If it's wider, it's taller. People always get confused with tire sizes if they cant see inches. Its simple math. 285, 265, etc is the width in mm. 75% of 285mm is more than 75% of 265mm.


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## Wilnip (Oct 4, 2011)

I don't see why a simple thread like this is making people argue. Simple answer, 4wd vehicles MUST have 4 tires of the same size.


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## 2COR517 (Oct 23, 2008)

Who is arguing? 

Vintage Steel is getting schooled. He's probably one of the few guys here that remembers buying passenger car tires with letters in the size. 
-Not that there is anything wrong with that.....

And the tires have to match. Not just size, but brand and tread should be the same. We've seen big difference in actual size between two different brands with the same numbers on the sidewall.


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## PR Fect (Oct 22, 2003)

I think this is great. A very good discussion on theory vs practice. I think most of us know its best to run all 4 tires the same. I also believe that if you looked at most trucks not all the tires wear the same. Yes I know that's why we rotate them. But the real question is, How much difference in tire height is too much? And how bad is it on the drive train? Not in theory, but in practice. Real life, yes I have tried that practice.


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## vintage steel (Nov 15, 2011)

...I stand corrected. I guess I learned something today.
Thanks for the skoolin'
-R


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## dlcs (Sep 2, 2004)

Any difference in tire height is too much. Even if the tire sizes are the same between two brands, the tires might still be a different in height. Just because the truck doesn't hop in 4wd doesn't mean you are not creating extra wear on the drive train.


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## Plowtoy (Dec 15, 2001)

dlcs;1490797 said:


> Any difference in tire height is too much. Even if the tire sizes are the same between two brands, the tires might still be a different in height. Just because the truck doesn't hop in 4wd doesn't mean you are not creating extra wear on the drive train.


 Yep, I will back this up 100% I had a customer (enterprise rent a car) who brought in their all wheel drive GMC safari for a jerking complaint at higher speeds. All the tires were the same size but they were 2 different brands. Turns out that the overall size was different and it was causing the transfercase to do weird things while going down the freeway. 
If you want to see if there is a difference in diameter, mark all tires at the 6 o'clock location with tire chalk, have someone walk next to the vehicle and watch one tire make 10 revolutions in a straight line and stop back at 6 o'clock, the rest of the tires should be between 4 o'clock and 8 o'clock per GM tech assist. Anything more than those numbers and the tires will have to be removed from the vehicle to prevent problems


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## dlcs (Sep 2, 2004)

Plowtoy;1490866 said:


> If you want to see if there is a difference in diameter, mark all tires at the 6 o'clock location with tire chalk, have someone walk next to the vehicle and watch one tire make 10 revolutions in a straight line and stop back at 6 o'clock, the rest of the tires should be between 4 o'clock and 8 o'clock per GM tech assist. Anything more than those numbers and the tires will have to be removed from the vehicle to prevent problems


Now thats a easy way top tell.Thumbs Up

Back in the day, I was into lift kits and big tires. I spent alot of time researching tires both height and width. What I found was that no two tire sizes were the exact same between brands. If i remember correctly BF Goodrich was always a 1/2 taller than other brands of the same size. I'm not sure how it is now but if you would look in a Dick Cepek or a Desert Rat off road catalog, they would give the actual tire measurments, not what was stamped on the tire.


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