Tire size

Wardsilverado · February 5, 2015

I am running 265/65/18 on the front and 265/70/17 on the rear of my 07 silverado 1500 four wheel drive. The diameter is 31.6 for both and the width is the same for both. The front differential on my truck went when I was plowing and my mechanic said the different size tires was the reason. But I don't agree because the tire diameter of the tires are 31.6 for front and rear so to me it shouldn't make a difference.

Wardsilverado · February 5, 2015

Well the gears didn't go which is why I disagree. The diff case broke where it bolts up to the upper bracket that bolts on the frame. The case broke free and dropped a bit causing the output shaft case that goes to the passenger side axle to crack and split. So to me the gears would have went first if there was an issue with tire size

kstruckcountry · February 5, 2015

Where are you getting that the tires are the same diameter? They are close but not exactly the same. That could be enough to cause a problem.

The other issue is you're using a plow on a half ton, which is asking for trouble if you ask me... I know plenty of people do it, but personally I would touch an HD that had plowed, let alone a half ton. Stuff is just more likely to break.

Wardsilverado · February 6, 2015

I was getting that the tires are the same size from the tire size calculator on the internet where you can compare tire sizes. It says they are both 31.6 inches high and 10.43 inches wide. I agree that half ton isn't the ideal rig to plow with but that's what I have. I have a 7 1/2 foot aluminum blade on it so with the minute mount 2 bracket and blade together it oy weighs around 400 pounds. Because I have an aluminum blade I don't work it hard at all. I work it harder in the fall when I'm hauling moose out of the woods and driving in the mud on woods roads.

Duelin · February 6, 2015

I think a more accurate way would be to measure the two different tires. You can have two different brands of the same size and they will measure different.

I was getting that the tires are the same size from the tire size calculator on the internet where you can compare tire sizes. It says they are both 31.6 inches high and 10.43 inches wide. I agree that half ton isn't the ideal rig to plow with but that's what I have. I have a 7 1/2 foot aluminum blade on it so with the minute mount 2 bracket and blade together it oy weighs around 400 pounds. Because I have an aluminum blade I don't work it hard at all. I work it harder in the fall when I'm hauling moose out of the woods and driving in the mud on woods roads.

8.1HD/ALLISON · February 6, 2015

+1 on measuring actual tires. Worn tires vs new tires can cause issues also. Any difference at all is wear and tear.

durandetto · February 6, 2015

What is the reason for having different size wheels front and rear?

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Btuggle88 · February 6, 2015

I'm kinda curious myself about the different size tires and rims.

kstruckcountry · February 6, 2015

Another issue is the 265/65 generally have less weight capacity, which = more squat, which = more difference in effective diameter.

Wardsilverado · February 6, 2015

The only reason for running two different tire sizes was because I had an 08 with the 265/70/17 and a 07 with the 265/65/18s I had got a large cut in the rear tire of my 07 silverado which had the 18s on it. Instead of going out and buying a new tire I just took the the rims and tires from the back of my 08 which had the 17s on it and put them on. I only did this after checking to see if the tire size was comparable on the tire size calculator site. Both tires have about the same wear and on the calculator site it said both are 31.6 high and the same width. To be safe I think I will just go back to running the same size front and back. Kinda costly replacing the front diff and output shaft so don't want to do that again. Although I must say it was a much easier job than I anticipated. Just had to remove the skid plate and cross member. Then unbolt the driveshaft and both axles. Unhook the connection for the actuator then two bolts for the carrier bracket on drivers side and two bolts for the output shaft on the passenger side and the vent hose. Putting it all back in only and bolting it up only took about an hour tops.

durandetto · February 6, 2015

You need to be running the same tires all the way around not just diameter but brand as well. Different tires have different tread depths which would cause the overall diameter to be different.

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newdude · February 7, 2015

For comparison sake, using OEM to OEM tires both wheel sizes, the Bridgestone Dueler AT RHS 265/65/18 is 31.5" overall diameter. The factory Goodyear tires, Wrangler AT/S and the Wrangler ST 265/70/17 are 31.7" overall diameter.

No clue as to what you have on both wheels. It's usually recommended no more than 2/32 tread depth front to rear on the same tires all around to keep any possible transfer case and driveline bind out of the picture. If the 18" tires are different enough overall diameter, you would get some binding for sure. Just don't always go by the tire size calculator. No two "similar sized" tires are the same. So if you have a Goodyear/Michelin/BFG/Hankook/Firestone/etc. they are all not 100% the same OD.

LaserBlueZ71 · February 7, 2015

You caused your own problems by being cheap.

Instead of replacing a tire, you rob another wheel/tire set from a different vehicle, seriously?!

You are using a half ton truck to plow snow, seriously?!

I think your different tire size contributed, but I think plowing with the half ton is what did the truck in. I don't care how light you think your plow is, when it has wet snow sticking to the blade, that 400 pound plow is now an 800 pound plow. If you were spinning your tires while pushing snow, which you probably were, you were putting big stress on that front diff to do all the work, since it has all the weight over it.

Half ton trucks are not meant for that kind of duty. If you want a truck that can take work and abuse, you need a 1 ton diesel, and even then I would probably upgrade to Dana or Eaton differentials with bulletproof housings. Factory components are not that strong when you start working a truck like you are.

As a mechanic, I am so sick and tired of people like you, who are too cheap to buy the proper equipment, and then maintain it properly. Once again, you did this to yourself, have fun opening your wallet now at the expense of your ignorance.

newdude · February 8, 2015

You caused your own problems by being cheap.

Instead of replacing a tire, you rob another wheel/tire set from a different vehicle, seriously?!

You are using a half ton truck to plow snow, seriously?!

I think your different tire size contributed, but I think plowing with the half ton is what did the truck in. I don't care how light you think your plow is, when it has wet snow sticking to the blade, that 400 pound plow is now an 800 pound plow. If you were spinning your tires while pushing snow, which you probably were, you were putting big stress on that front diff to do all the work, since it has all the weight over it.

Half ton trucks are not meant for that kind of duty. If you want a truck that can take work and abuse, you need a 1 ton diesel, and even then I would probably upgrade to Dana or Eaton differentials with bulletproof housings. Factory components are not that strong when you start working a truck like you are.

As a mechanic, I am so sick and tired of people like you, who are too cheap to buy the proper equipment, and then maintain it properly. Once again, you did this to yourself, have fun opening your wallet now at the expense of your ignorance.

Well now...1/2 ton trucks can plow and have been used for a long time. IF you have one with plow prep (regular cab only 1/2 ton) they are rated for 500lbs of plow and 50-75lbs of truck side hardware. And you also don't "need" a 1 ton diesel to plow. I can't even count the number of 2500hd gas and diesel trucks with blades hanging off the front of them.

LaserBlueZ71 · February 8, 2015

Well now...1/2 ton trucks can plow and have been used for a long time. IF you have one with plow prep (regular cab only 1/2 ton) they are rated for 500lbs of plow and 50-75lbs of truck side hardware. And you also don't "need" a 1 ton diesel to plow. I can't even count the number of 2500hd gas and diesel trucks with blades hanging off the front of them.

Even with plow prep, this user is only 100 pounds shy of the maximum, and the plow prep package doesn't change the fact that you still have a light duty drive-line, including the front differential. The prep package just allows you to put a plow on, it doesn't upgrade the hard parts of the truck that matter. One also has to account for snow that sticks to the blade, which weighs a heck of a lot more than people think it does. Sorry, i should have been more specific, any of the big 3 3/4 and 1 ton trucks would be great for plowing, not just 1 tons.

Modern front differential housings are pretty poor from the factory, made from cast aluminum it doesn't take a lot to stress fracture them or stretch the metal.

Sorry to the poster if i was a little bit rough with my reply, but I see this kind of stuff day in and day out, and it just frustrates me when people won't take ownership for the damage they caused themselves. Being cheap never pays, in the end it costs you more.