2nd Gen Non-Engine/Transmission Dual Wheel Offset

[WrenchRat]

Question for you dually guys:

What, if any, is the difference in offset between the 94-99, 16x6, 4 hole design and the 2000-2002, 16x6, 7 hole design?

I'm currently running 255/85-16's on my '99 and they are just touching with only the camper shell as load and 45psi. I could bump the psi up, but the difference is minuscule and the ride gets real nasty. You know what I mean on the ride.

I'm trying to come up with the most economical, correct and safe way to increase the gap. And I'd really like to stick with the 255's as it is a help on deeply rutted back roads. I also have virtually no interest in going to aluminum rims at this point.

Thanks

 

[WrenchRat]

94-99 vs 00-02 Offsets

Still hunting for this after a few phone calls. Not even the Dodge dealer could help. #@$%! Nice guys, but don't have access to such info.



Not seeing it on web searches either. Southwest wheel had the G3 rims, but no reference to G2's. Guess I'm down to hunting through salvage yards for a sample to measure... Or sneaking a measurement in a parking lot if someone is running 'naked' rims.



Surely somebody here knows the answer to this question? I'd much rather spend the $$ on rims and avoid the complications of spacers.

 

[Road Dog]

The rule of thumb, as I've read here, is:

If it came with 215s then you can run 235s.
If it came with 235s then you can run 255s.

The OEM tire size is on the VIN label on the driver's door jamb.

 

[icman95]

I think it's possible that part of your problem it the psi. I'm not sure how much will change if you bump it up, but 45 sounds a bit low to me as the recommended psi on my 01 is 55 rears and 65 front. If the pressure is too low then the sidewalls will squat down too much and touch. This is why the owners manual warns against airing down the rear tires on a dually when offroading. Having said that, I only have 235s on mine and can see where a bigger tire might take up most of the rest of the space in between.

 

[Grizzly]

I think it's possible that part of your problem it the psi. I'm not sure how much will change if you bump it up, but 45 sounds a bit low to me as the recommended psi on my 01 is 55 rears and 65 front. If the pressure is too low then the sidewalls will squat down too much and touch. This is why the owners manual warns against airing down the rear tires on a dually when offroading. Having said that, I only have 235s on mine and can see where a bigger tire might take up most of the rest of the space in between.

I have to disagree with you. I run as low as 40 psi on my rear dual 235's when the truck has no load. Running 55 on the rear when empty will wear out the centers. When towing the 5er, I run 55 psi on the rear duals. I run 65 all the time on the front tires. I also do not believe in running any larger size tires then the truck was designed with.

 

[WrenchRat]

I have to disagree with you. I run as low as 40 psi on my rear dual 235's when the truck has no load. Running 55 on the rear when empty will wear out the centers. When towing the 5er, I run 55 psi on the rear duals. I run 65 all the time on the front tires. I also do not believe in running any larger size tires then the truck was designed with.

For the record, the door jam sticker tells me that for the stock 215/85-16E's max pressures, COLD, are 70psi front and 65psi rear. Those were Michelin



I agree. When I ran 235's, I 'learned' that the correct pressure for unload/light loads was around 40-45psi. After talking to other dually owners, 45psi is fairly common for no load or very short loaded runs. This was the best pressure for even tire wear with a side benefit of a better ride. If I left over 55psi in them, accelerated center wear was the result, on top of a nasty ride. I never ran more than 65psi on the 'E' rated rear tires under heavy load for the same reasons. My loads never exceeded ~10K via bumper pull. Maybe the additional bed loads of a 5er or a goose neck trailer might justify full 65-70psi. I never noticed (I do my own rotations every ~5K miles) any contact pattern between the rear duals with the 235's.



The same logic applies to the D rated 255's (65psi max). I usually run 55psi in the rear when pulling and have 'screwed up' and left 55psi in them and sure enough, the center wear accelerated. The tires still just touched at 55psi without the trailer. And when the trailer(s) is hooked up, it's more than just touching.



I'm getting ready to make a 5000m run with a trailer and am trying to get this, at the least, improved before I go. As far as I can tell (unconfirmed), the 94-99 rims have a 5. 00 offset and the 00-02 rims have a 5. 35 offset. If this is true, that means I can get an additional 0. 70 gap running all four. Might be enough and no adapters would be necessary. If I only run one on the outer of each side, that would certainly improve things.

 

[ihegdal]

Regarding the offset question, the 2000-2002 rims have 3/8" more offset for a total of an additional 3/4" between rim beads in the dually configuration.

 

[georgej]

On my 2001 3500 the door label PSI's are 55 front and 50 rear. As far as the offsets I couldn't even find that info in the factory manuals

 

[WrenchRat]

Thanks for the replies guys.

Yeah, I doubt that the offset info is published much of anywhere except at rim manufacturers or aftermarket folks. Simply a minor design issue that 99% of the folks out there don't care about.

I've called all the known boneyards in the area (>6) and not even a used 00-02 Dodge dually rim to be had. I even called two places that sell industrial truck rims and no dice on new ones. Rather odd I thought. I'll expand my search out a bit, but at some point, it ain't worth the time and money for travel or shipping to get the beasts. While I'd much prefer the simple route of either two or four rims, it's possibly time to consider another option...

At this point, I'm investigating simply putting in longer studs, machining a simple one inch spacer(s), buying a used Chev rim(s) with the 4. 60 bore and opening it up to a nominal 4. 72. On our Dana 80's, the 4. 78 nominal step diameter for piloting the rims is only about 0. 50+ long and then it steps down to the 4. 72 diameter. With a one inch spacer, that puts the outer rim on the 4. 72 diameter. Which is where the smaller diameter Chev rim comes in. Going this route simplifies machining of the spacer and avoids a very small pilot flange thickness that might well fail. 4. 78-4. 72=. 060/2 = . 030/side or . 030 thick.

Surely there are some used 00-02 rims out there somewhere?

 

[Forrest Nearing]

I have to disagree with you. I run as low as 40 psi on my rear dual 235's when the truck has no load. Running 55 on the rear when empty will wear out the centers. When towing the 5er, I run 55 psi on the rear duals. I run 65 all the time on the front tires. I also do not believe in running any larger size tires then the truck was designed with.

no larger than the largest factory installed tire or no larger than the tire that was optioned for that specific VIN?

 

[WrenchRat]

Quote:

Originally Posted by Grizzly View Post

I have to disagree with you. I run as low as 40 psi on my rear dual 235's when the truck has no load. Running 55 on the rear when empty will wear out the centers. When towing the 5er, I run 55 psi on the rear duals. I run 65 all the time on the front tires. I also do not believe in running any larger size tires then the truck was designed with.

no larger than the largest factory installed tire or no larger than the tire that was optioned for that specific VIN?

Good question Forrest. Maybe Grizzly can expand on his comment?



Heck, I almost never run the stock size tire on my vehicles. And on 4x4's I run as large a diameter as possible without a lift or a lift of a few inches. Yes, I'll change gear ratios and speedos to suit. Not a big deal. Those of us that live in the sticks that frequent poorly maintained gravel roads or farm tracks need as much diameter as possible to keep the pumpkins out of harms way.



I have NEVER had a significant problem going with larger tires (up to 35's) on full size trucks. Sure you can argue braking power loss, but it's never been enough with HD trucks to cause me an issue. Unless you flat abuse the trucks by jumping, etc. , the axles, bearings and U-joints, properly serviced will be fine.



And I'm sure there are guys out there that run MUCH bigger on 3/4HD and 1 Ton trucks. Often, the lifts are where the issues begin (lift quality, driveline angles, stability, etc. ). It's been my personal experience that once you go past ~35inch diameter, complications/issues are more likely to exist. But with proper engineering, they can be readily solved.



So, I see absolutely NO reason that a larger tire (YMMV) should cause a problem of any real significance on our HD Dodges. My tire contact issue with the duals is simply something I prefer to fix. I've run over 30K miles with them the way they are and could likely run another 10K or 15K to the point where the tread is worn out... I could easily ignore it, but it's buggin me.

 

[Grizzly]

Good question Forrest. Maybe Grizzly can expand on his comment?



Heck, I almost never run the stock size tire on my vehicles. And on 4x4's I run as large a diameter as possible without a lift or a lift of a few inches. Yes, I'll change gear ratios and speedos to suit. Not a big deal. Those of us that live in the sticks that frequent poorly maintained gravel roads or farm tracks need as much diameter as possible to keep the pumpkins out of harms way.



I have NEVER had a significant problem going with larger tires (up to 35's) on full size trucks. Sure you can argue braking power loss, but it's never been enough with HD trucks to cause me an issue. Unless you flat abuse the trucks by jumping, etc. , the axles, bearings and U-joints, properly serviced will be fine.



And I'm sure there are guys out there that run MUCH bigger on 3/4HD and 1 Ton trucks. Often, the lifts are where the issues begin (lift quality, driveline angles, stability, etc. ). It's been my personal experience that once you go past ~35inch diameter, complications/issues are more likely to exist. But with proper engineering, they can be readily solved.



So, I see absolutely NO reason that a larger tire (YMMV) should cause a problem of any real significance on our HD Dodges. My tire contact issue with the duals is simply something I prefer to fix. I've run over 30K miles with them the way they are and could likely run another 10K or 15K to the point where the tread is worn out... I could easily ignore it, but it's buggin me.

When my 95 Dodge dually was in need of new tires at 55K miles, I wanted to go to a 235/16 instead of the original equipped 215/16. I always thought that the 215's looked like little baby tires. I called a Dodge Factory Rep and asked the question if that was advisable. He responded that for one it could void the remainder of my extended warranty. He also said that the my 95 Dodge DRW was designed to handle best with the 215/16" tires. Using any different size tire would effect the ride and handling characteristics and braking. He strongly advised me to stay with the size tire my truck was originally equipped with. He also explained to me the important's of maintaining the correct air space between the dual wheels for proper cooling.



I can tell you're sold on your ideas about what size tires you want to run on your truck and that's fine. I likewise will do what I feel is right for my truck.

 

[WrenchRat]

Grizzly,



And yes, I agree the 215's were tiny in proportion to the truck. Actually, the handling on my truck improved significantly when I went to 235's (less understeer for one thing).



Each of us has to do what we think is best for our own circumstance. I did not intend any offense at asking for your reasoning. My apologies if so taken. I just found it curious after modifying so many vehicles and years of doing otherwise on tires, etc. What follows is friendly gearhead conversation...



Sounds like the Dodge rep gave you the 'company line', which is supposed to be the 'default' position they take with the public. I have worked directly with engineers and tech reps in Detroit at the major car companies as well as T1 suppliers in a design capacity. If they don't know you, even an engineer, you will get the established, safe comment for their protection, not yours and mine. It can be impersonal at times, but that's how the system operates.



I've been on the 'rep' side before as an Application Engineer dealing with field calculations and fatigue values for customers. I too had a 'company line' that I gave to customers, as it was required by our firm. (Legal eagles said so. ) However, I was not opposed to discussing alternatives and trying to be realistically creative in helping a customer get a problem solved, as long as it was at least physically safe (also part of the job). Many engineers that I ran into were of the same mind/attitude as soon as they could see you were a reasoned person, could understand most of what they were talking about and were sincere in your intent.



I really doubt if changing tire size would void a new car warranty unless there was damage directly attributable to such activity, which is highly unlikely. Just like someone saying that if you don't use MOPAR oil and have it changed at the dealership, your warranty will be voided. Not true. See Magnuson-Moss Act.

 

[ShortB]

Try Car-Part.com



There's tons of the wheels you're looking for around my area. Looks like they basically run anywhere from $35-$125ea for the '00-'02 3500 wheels.

 

[WrenchRat]

Bingo! Did a search for the region and got a few more leads. Thanks ShortB!