Converting from 17 to 19.5, center hole question

[outdoorsguy36]

i have a 72' chieftain with the 17" five lug split rims. I found a 1997 airstream motor home that has 19.5 five lug rims with the same bolt pattern but the center hole is bigger at 7 1/4". My question is can I still use these rims or the bigger center hole will cause a problem?

[Rickf1985]

I don't think the center hole is an issue but the issue will be that the 19.5 rims are flat at the lug holes and were designed to be lug-centric on the 19.5 hubs. Therefore they centered on the lug studs and you use a special adapter plate that is coned on the nut side and flat against the rim to tighten the rim against the hub. This way it can not move radially around the on the hub. You have to have 5/8 lug studs I believe they are. And the special lug nuts and adapter plates.

[87Itasca]

Isn't the torque on the rears something like 425 ft. lbs?

[Rickf1985]

180 ft. lbs.

[tmsnyder]

German torque specification: Gudhentite

[turbinebronze]

Do be carful with the torque of the lug nuts. My '69 Travco (Dodge M-375 Chassis) lug nuts are at 400 ft lbs!

[Rickf1985]

It is a 5/8 lug stud, 180 is the spec. !80 is what GM calls out for the lug torque. What size wheel studs do you have? At 400 Ft.lbs. they would have to be close to one inch studs to handle that torque. The lug nuts would have to be around 1 7/16". Just looked it up, 7/8 inch wheel studs call for 400 ft. lbs. of torque. That is a monster stud and is used on big trucks. Are you sure that is what you have? If you have the standard 5/8 studs and you are putting 400 ft. lbs. on them you are courting disaster!

[outdoorsguy36]

I decided not to go with the rims from the airstream because I found a 1980 Winnebago chieftain that has exactly identical rims that are 19.5". the center hole and the lug holes are identical to the 17" rims I have now except the 19.5" rims are radial instead of split.

[Rickf1985]

Make damn sure the lugs are going to tighten properly! The 19.5 uses a steel lug adapter between the rim and the lugs. Not saying this will not work but I find it hard to believe someone else has not figured this out in the last 20 plus years. There must be a reason why more people are not doing it. The GM 19.5 rear hubs are machined to fit the wheel perfectly and the front hubs have bosses on the hub for the wheel to center on so make sure your Dodge is hub centric and it will perfectly center the wheels on the hub and put none of that weight on the lug nuts.

[outdoorsguy36]

I measured everything from the center hole, lug holes, lug posts, lugnuts and even the inside where the rim meets up with the brake drum. Everything was identical except the rim is a radial and 19.5" instead of 17". I had heard from a RV salvage in Nevada that there were a few dodge chassis RV's produced in the 80's that had radial 19.5" rims that would match up I had just never seen any. This is the first instance were I actually found some that seem to be identical and ive been looking in junkyards for several years. I hope that this works and by next month I should have tires on them and mounted. I'll update this thread once I get them installed if it works or if I have problems. As far as an adapter the winnebago these came off of didnt have any type of adapter the lugs were slightly cone shaped on one end and tightened onto the rim. This is the inside dually rim, I had already taken off the outside dually they were just bolted together wit the lugs. This is exactly how the rims are on my 1972 so im thinking it will work. I really appreciate the feedback and help and it will be about a month so mid October and I should have an update

[Rickf1985]

That inner rim is centered on the tapered Budd style lugs, so the outer will be centered by the tapered lugs. I have never seen a set of rear dual 19.5's in five lug. This is a new one on me as are the Budd lugs. What brand is that chassis?


Sorry, removed the formatting that went in on it's own???

[Elandan2]

The Dodge M 500 chassis was built with 5 lug 19.5" Budd type disc wheels. The wheels are tightened to 450-500 ft. lbs torque.

[Rickf1985]

Sure as hell not the type of torque you are getting from a tire iron!! Gonna have to invest in a pricey geared lug wrench. This one in the video is real nice for taking them off but that gear ratio is not good for torquing them back. You will need a 3 or 4 to one geared multiplier for that so you can use a torque wrench and calculate the torque. See second link for that. This will also work well to get the nuts off.


https://www.youtube.com/watch?v=0OY40gkE0N8


https://tengtoolsusa.com/products/teng-tools-mp2700-3-4-inchfemale-1-inch-male-torque-multiplier-max-3000nm?variant=10586103250987&cmp_id=1473440120&adg_id=58755097404&kwd=&device=c&gclid=CjwKCAjw54fdBRBbEiwAW28S9q_fpT9uPjXCPP-WKAdnDpKPn4Sf-tYI4UelaWB5rXKNZMvFXlpYUBoCrT8QAvD_BwE

[Elandan2]

I have found the easiest way to take them off is at the tire shop or using my little plastic card for roadside assistance!!  :)rotflmao

[Rickf1985]

True, but what exact torque is that one inch impact wrench set at? The torque for my P30 is 180 ft/lbs. and after the tire shop mounted the tires and did NOT balance them I had to take them off and balance them myself. I had to use a ten foot pipe on a 3/4" drive breaker bar to get the lugs off. I have debated on replacing all 30 studs ever since then.

[DaveVA78Chieftain]

In 1980 Winnebago used both the Dodge and GM chassis.  Due to the length, a 29 ft 1980 Dodge based Chieftain would have used a Dodge M500 chassis which has the following wheel specs: Double Lock Nut, 5 Stud, 8.0" Bolt Circle, Radial Tubeless, 19.5"x 6" Rim.

The 1980 lug nut dimensions mate up with a 72 Dodge M375 Chassis: Double Lock Nut, 5 Stud, 8.0" Bolt Circle, Split Ring, 17"x 6" Rim.

Both rims (M375 & M500) used:
3/4"-16 nut on front rim and inner rear wheel rim.
1 1/8"-16 on rear outer rim

M375: 400-450 ft-lbs torque
M500: 450-500 ft-lbs torque

I do not know if
1) the center holes are identical
2) the wheel offsets are the same.
3) If the 19.5" tire will fit in the 17" wheel well.

My 1977 Dodge M400 chassis with 17.5" rims requires 300-350 ft lbs of torque.  Being a fairly small guy, I have to use a 3ft cheater pipe in conjunction with a 3/4" socket set.  It only requires 100 lbs of force at a 3ft from the nut to obtain 300 ft-lbs of torque.  Being a small guy, that is the only way I can meet the torque spec.  Using a 4ft cheater pipe that same 100lbs of force (e.g. 100lb weakling) would = 400 ft-lbs @ 4ft from the nut.

[outdoorsguy36]

The 1972 chieftain D-24C that I have is on a dodge 375 chassis with a 413 engine. The wheels are mounted the same way on mine with the tapered lugs. Awesome specs DaveVA78Cheiftain thanks, I tried to find this info but couldnt.

[postman]

Sure Dang Glad I bought a torque multiplier 

[legomybago]

True, but what exact torque is that one inch impact wrench set at? The torque for my P30 is 180 ft/lbs. and after the tire shop mounted the tires and did NOT balance them I had to take them off and balance them myself. I had to use a ten foot pipe on a 3/4" drive breaker bar to get the lugs off. I have debated on replacing all 30 studs ever since then.

I just replaced my brake drums, and found 5 bad studs due to over torqueing from a sweet tire store when I had my new tires put on a few years ago, AND I asked them not to crank them down as tight as their 1" gun would go, well of course they are going to, for liability reasons....After I got it home I thought I better see if I can loosen the lugs...nope. I brought the rig back the next day and had them back them off one by one as I retightened them with my large tire changing tools that I carry in the rig. If you ever plan on changing your own tires, you better do this. Or you will be on the side of the road twittiling your thumbs...