Thread: Dually Tire Swap

I have an '02 chevy dually with stock Wrangler 215/85 r16 and want to change to 235/85 r16 wranglers. On my '93 Chevy I had 235/85's and they were very close to touching without a load. I was wondering if any one has made the swap and what the clearance is. I usually scale at 35,000#'s when loaded so if they flex to much they will rub. I am mostly wondering if they changed the wheel spacing with the new body style.

Originally posted by rolloffhill
I have an '02 chevy dually with stock Wrangler 215/85 r16 and want to change to 235/85 r16 wranglers. On my '93 Chevy I had 235/85's and they were very close to touching without a load. I was wondering if any one has made the swap and what the clearance is. I usually scale at 35,000#'s when loaded so if they flex to much they will rub. I am mostly wondering if they changed the wheel spacing with the new body style.

I doubt that the offset of the stock rims would be suitable for 235s. As you said, if they flex too much they'll rub, but to reduce the flex by raising pressure would likely lead to worse problems. Also, remember that even if they don't actually touch you increase the risk of odd stuff getting wedged between them as they get closer. BTW, what need do you think you have for 235s ?

PS to my last message.
At 35,000# aren't you just a weee bit overloaded ? What is the GCVWR for a 3500 ? I assume you're on a CDL for this rig (-:

Well, A 235/85R16 in a 10 ply or LRE will carry Approximatley 11,112 lbs. on that axle, at 80 psi. So the rest of your weight has to be on the front axle and the trailer tandems that I would assume would be dual. So, if they are 235/ LRE's then, you should be able to load that vehicle that heavy. Your front axle should pick up the balance.

However, I can assure you with a high degree of certainty, that if you put the 235/s on those rims, you will kiss the duals on the back, loaded that heavy, and those tires will fail in the sidewall, that is a guarantee.

If you have a 215/85R16 LRE or 10 ply, then you are overloaded in your current situation. Those tires are good to 9880lbs/axle, at 80 psi, so you are overloading them at 35,000 pounds. you would have to put 6000 lbs on the front axle, and you can't do that.

The bad news is, that I don't know if there is a 16 inch wheel made with an offset that is angled enough to fit the 235's in. I suppose if there is not, you could look at a spacer of some sort to seperate them. Of course then you run into lug stud length issues. Anyway, that gives you something to consider.

Good Luck.

The trailer has tandem duals on it. The reason I want to go bigger is to keep the tires cooler. I do most of my hauling in the hot summer months with alot of weight, so every thing I can do to keep the tires cooler is a plus. Also BTW I do have a CDL. Like I said before I had 235's on my '93 454 and never had tire sidewall problems or blowouts. Granted I am loading my Dmax a little more now because it can handle so much more weight than the old 454. I love this truck, it'll run circles around p'strokes. Plus I love the look of a little more sidewall on the truck.

also Duromx04

What do you think of spacing the wheels out, I am a little leary of that myself. The Goodyear dealer near me suggested that, but I don't know.

Thanks

I am not really that wild about using spacers myself. The main reason is because you will be the outside tire further out and away from the axle, and I think that will make it weaker. It would be harder on your lug studs for sure.

Check with some wheel manufactures and see if there is a wheel made for 1 ton duallies that has a more severe offset to handle what you are trying to do. If so, that would be the way to go. I have seen guys put 235's on them and they almost always kiss together.

Good Luck

I have a 2003 gmc 3500 with 235/85/16 on alcoa rims same ofset as stock rims and use a 1/4" aluminum spacer and stock wheel studs tires never touch even fully loaded with 4,000lb

The Goodyear dealer down here told me that it would be about a 1/4" spacer, I guess that seems to be right. Where did you get them? Are they machined solid billet aluminum? Also do the tires stick out of the fenders and fling mud? Just curious.

Originally posted by rolloffhill
The Goodyear dealer down here told me that it would be about a 1/4" spacer, I guess that seems to be right. Where did you get them? Are they machined solid billet aluminum? Also do the tires stick out of the fenders and fling mud? Just curious.

He is considering tires that are 2cm wider, slightly over 3/4 inch. Each one of them only encroaches on the gap by 3/8. 1/4 inch spacers would still leave him with 1/2 inch less space between the tires. Then there's the added track and additional wear to deal with, but he wasn't concerned with that. I wouldn't expect the additional 3/8 on the outside to be much of a mud sling problem, though I suppose a REALLY nasty cop could write a ticket if he/she thought there was inadequate coverage of the tire.

Drunk on Diesel,

If you only have 4000 lbs on the back axle of your truck, then you really are not loading that truck at all. Rolloffhil is putting about 11,000 lbs on his axle. That makes a big difference. However, a 1/4 inch spacer is pretty thin, so it might not make that much difference as far as stress goes. I still would do some more research on it, because of the heavy loads you are hauling. The space between doesn't have to be huge between, just enough so that no matter how big of bump you hit, you won't kiss the duals together.

Originally posted by Duromx04
Drunk on Diesel,

If you only have 4000 lbs on the back axle of your truck, then you really are not loading that truck at all. Rolloffhil is putting about 11,000 lbs on his axle. That makes a big difference. However, a 1/4 inch spacer is pretty thin, so it might not make that much difference as far as stress goes. I still would do some more research on it, because of the heavy loads you are hauling. The space between doesn't have to be huge between, just enough so that no matter how big of bump you hit, you won't kiss the duals together.

That space was figured for the stock tires on the stock rims at the design load. To maintain it would take slightly more than 3/4 inch (2 cm) assuming the sidewalls of the wider tires deflect the same amount under load (a questionable assumption, I know). Personally for 35,000 # I think he just needs a 1 1/2 or 2 ton truck (-: With 19s.

Ask Broker, I think he has 19.5's on his D-MAX's, that is probably the best route to take. And probably not too much more expensive than buying 6 new wheels, or risking the use of spacers.

The 235/85R16 will deflect more than the 215/85R16 because they have more sidewall. They both have an aspect ratio of 85 meaning that the sidewall is 85% of the cross section width. So, an example would be on a 235 the sidewall is 85% of 235mm which is 199.75, or 200.
85% of 215 is 182.75, or 183.
So, you have 17 more mm of sidewall in the 235's than the 215's which would cause more sidewall flex at a given load for a given pressure.

Now, the one thing to consider is that the 235 has a much bigger air chamber, so it can carry more weight at a given air pressure. So that throws a little twist to it.

Aspect Ratio is defined as the relationship between sidewall height and cross section width.

If you had a tire that is a 235/100R16, then the sidewall would be exactly the same height as the width. In this case 235mm
If you had a tire that is a 235/75R16, then the width would be the same, but the height of the tire would be much shorter. 25% shorter than the above example.

Cross Section width is defined as the width at the widest part of the tire in mm. The fattest part is between the two sidewalls, not the tread itself.


Hope this makes sense.

rolloffhill The Goodyear dealer down here told me that it would be about a 1/4" spacer, I guess that seems to be right. Where did you get them? Are they machined solid billet aluminum? Also do the tires stick out of the fenders and fling mud? Just curious




I found the spacers at a alcoa dealer in westwood. mass. $ 25.00 for a pair R.H. SCALES CO they are just machined aluminum not billet unless you want to pay a lot more for something you can't see.The tires don't seem to stick out much more or fling mud. I have 20.000 mile on this setup with total GVW of 19.000 lbs tires never touch at 75psi: