Different size tires on each side of my dually?
 

Is there anything wrong with running 2 different sizes in tires on the rear dual wheels? Such as, the left side inner and outter tires are diff, and the right side inner and outter are diff? I dont have the exact measurements right now (but could look if its an issue) but the inner tires are noticeably larger (taller.. dunno about wider) than the outters.

Does this affect anything?

ya it'll knock your rearend out.

yup what he said and wear your tires fast

Whaaa? It will mess my rearend up? I'll get the exact measurements tomorrow but this is not good news. Will this impact traction and economy?

It will. Why would yo run different sized tires?

do you have a posi or limited slip diff in the rear?

you could get away with it if you have an openend ... but its still better to have all the same tire

You need the same size tires out back...all 4 of em. When I bought my '97 Dually (just sold) it had 157k on it with decent Cooper Discoverer ATR 235/85/16's out back, no telling how many miles were on them when I bought the truck. I kept those tires on the rear for over 3 years, and balanced them and rotated them from side to side, but they always remained on the rear. I sold the truck with 216k miles and the tires passed state inspection with flying colors maybe 1000 miles prior to selling the truck. That's 59,000 miles that I put on them! That tells me two things... 1-those Cooper's rule, 2- maintaining the rear tires makes them last a very long time. Moral of the story...if you want your tires to last, run the same size out back. Tires aint cheap, keeping the pressures even and always rotating/balancing them will prolong tire life. If one tire is newer or taller than the tire next to it...it will take the grunt of the weight and wear out faster. Traction will also suffer. The other (smaller) tire will constantly be scuffing the surface of the road and eventually become out of round. This also goes for tires with uneven pressures.

i never thought about the thread difference, thats a good thought. :tu:

cmon use your noggin:argh:

Bought the truck like that.. they have diff treads, sidewalls and maybe even widths.

Judging by my limited burnouts, its a limited slip.

How much were those coopers? I really dont want to get new tires but if my current tire situation is poor then I guess I really need to :(

Says a klein :lol: lol


Oh and for my info, how do I fill up both rear tires? I see one fill spout coming out the rear wheel somewhere, but what about the inside tires? How do those fill?

Says a klein :lol: lol

thats right:c:

Ok so heres the deal. The tires in the rear are ALL 245/75/16. 3 of the rear tires are the same tire/tread pattern, but on the ds inside rear the tires is diff and has taller lugs. They are the same tires, but the inside tire is OBVIOUSLY higher than the outside tires. The front tirese are 235/85/16, which I THOUGHT was the right size tires for this truck? What does having a shorter tire in the rear do for mileage count and economy? I'm pissed now and i'm going to go ocd over this and get new tires I think.

when you run mis-matched tires on either side of the axle, you spin your spider gears inside the carrier at double the rate of speed of the axle speed. Spinning the spider gears that way will SMOKE your rear axle. Normally, the spider gears hardly turn while running down the road, unless or until a tire is spinning or you are going around a corner. Running them constantly is BAD. If you have a posi (limited slip) the clutch plates are probably gone by now.

I'd be surprised if the entire carrier assembly is not already toast. Count on spending some $$$ if it is. Costs way more to set up a new rear carrier than to put the right tires on the truck. Even if you have to run used tires, get 'er done.

Same deal with 4x4 trucks, BTW, except that you smoke the transfer case instead of the carriers.

This may help illustrate the issues:

HowStuffWorks "Open Differentials"

^^ as always - excellent post ^^

What I'm saying though is the rear tires ARE all the same size, except they are 245/75/16 and the original tires for this truck are 235/85/16. One tire in the rear is mixmatched but is still the same size as all they others.

If all the tires are the same size - you shouldnt have any problems at all.

My issue is, what is running a 75 sidewall and 245 width, as opposed to the 85 sidewall and 235 width going to do? I've heard running the duals this wide without spacers is bad for them? Even though they dont touch. And what does running the shorter sidewall do for the speedo and mileage?

the 245/75/16 is about the same height tire as what comes factory on these rigs 215/85/16. the 235/85/16 rub in the front when turning without trimming the plastic inner fender. the 245s will rub on back if you put a good load on it but are fine just driving.

Oh ok so as long as there is no load I'm good? Wont the slightly smaller sidewall eat up more gas or give me incorrect speedo readings?

One or two tire sizes won't make that much difference in fuel economy, but can change speedo readings for sure. Borrow a Tomtom or some other GPS and take it for a drive. See if the speedo matches the GPS. If not, make a change in tire size (seems like that is best for you), change the speedo gear, or learn to live with doing calculations in your head when you drive.

General rules of thumb:

Wider tires eat more fuel.
Taller tires eat more fuel.
Heavier tires eat more fuel.
More plys eat more fuel.
Bias ply eats more fuel.
Aggressive tread eats more fuel.

So, properly sized, skinny, light, radials with street tread, will give the best economy in most cases. If fuel economy is the desired goal, purchase tires accordingly. On the other hand, if you need to haul heavy loads, drive through mud or snow, pull a trailer, need to gear lower, etc., then pick tires that will help in that regard and stop worrying about fuel mileage.

I thought a taller tire would help reduce fuel consumption on the highway?

yes you are right TALL tires reduce fuel mileage

Wait you just contradicted what I just said.. tall tires should HELP fuel mileage because the motor is turning less rotations per minute at the same exact speed as opposed to having tiny tires..

ya i just reread. the taller tire may help fuel mileage if your just driving but having the tires the proper size helps when towing. also if you run 235s watch your speed they will throw it off some

Having the taller tire on the left inner is going to put most of the load on that tire and cause the outer tire to spin a little bit faster, depending on the actually overall difference. If theres a BIG difference it might wear the smaller tire faster than the rest. As HAYMAFIA mentioned the 245/75R16 is really close in height to the 215/85R16 that came stock. Biggest difference is the 245 is more available and a touch wider. But as far as the 235/85R16 rubbing in the front i have never heard of. 99% of the Dually's i see are running the 235/85R16 all around. Hope this helps.

mine always rubbed the inner plastic. i just trimmed them or took them out completely. this is on a 2 wheel drive

you shouldnt have to worry about your speddo unless you go up a couple tire sizes, i ran 265-75-16 and 285-70-17 and the speddo was only off like one or 2 at 70 mph,
but now i have 285-75-16 and its off little bit i can tell, im gunna check it out this summer when they put those speddo things up on the side of the road