Our last Barth (she now owns Marvin+Doris) was a 1989 25’ Regal with the shorter P-30 chassis with 16” wheels and 454 engine. The data tag showed front GAWR as 4880 lbs, limited by the tire capacity at 65 psi, and rear GAWR as 7500 lbs, limited by the suspension because the tires could handle up to 8560 lbs. That’s a total of 12,380 for GVWR. We towed a 2800 lb VW Cabrio on a dolly with inertia brakes; can’t remember the dolly weight but do remember the total was within the GCWR. We put a lot of miles on the combination with no particular problems other than some slowing on the steeper grades. I had a GM spec sheet or booklet that had the GCWR’s for the 1988 P chassis; Marvin+Doris probably still have it. Barth provided the hitch, welded to the chassis. It had a 2” ball, and I’m sure it was a Class III.

It’s hard to imagine anyone replacing 19” wheels with 16”, even if the bolt holes lined up. The effect on speedometer, odometer and engine rpm for a given mph would be significant. It just doesn’t make sense. I agree with Doorman – Barth more than likely just “screwed up the data tag”. We purchased three different new coaches from them and spent a lot of time at the factory and in correspondence with them. They built great coaches, but their internal control systems were not particularly impressive. I could see where the wrong data could easily get onto a data tag.

Just as a side note, we tried stepping up to a 1989 28’ Regal that was built on the larger chassis with the 19” wheels. To quote my wife, “It rides like a truck.” We went right back to the 25’ with the smaller chassis and got the smooth ride were used to in our 1978 24’.

Bill Beard
Barth Owner Emeritus (three times)

quote:

How many lugs do the front and rear wheels have?

Bill h , the front & back wheels have 8 lugs.
WOW , im soo glad you asked me that question. the covers on the back crome wheels were a bear to take off . i will definatly be keeping a rubber mallet in the barth incase i have a flat on the road .

Speaking of wheels & tires . the data tag states 70 psi for the front & rear tires . now is that for the 19.5 they have listed ? what do you guys recomend for my 16 in ?? the tires state 65 psi cold on the sidewall for single & dual .


(Quote) There could be all sorts of fun answers to this:

1. A special customer order wanting more ground clearance

K&E , i would have less ground clearance with the 16 in wheels wouldn't I ?



(Quote)Bob, checking you Vin # (4th pos. J) your brakes are 10,000-14,000 gvw range. ours is K, 14,000-16,000. I have rear disk. I think Barth screwed up your data tag. By the way they also gave me your center consol. 3339 on the back of mine. No you can't have it back. I think you will find that you have the power to tow anything under the 5000 lb. with out any trouble. I would highly recomend a trans temp gauge. Keep a good eye on the water temp.

Doorman , i didnt notice the vin , but yes its a J . and the data tag states 14,5000 gvwr . Also the trans temp gauge is on my to do list .

Thanks again , Bob

quote:

Originally posted by crouch38:

quote:

How many lugs do the front and rear wheels have?

Bill h , the front & back wheels have 8 lugs.

That seems unusual. My 19.5s have ten lugs in back and use every other hole in front, for five lugs. I didn't know they made 8 hole 19.5s.

quote:

Speaking of wheels & tires . the data tag states 70 psi for the front & rear tires . now is that for the 19.5 they have listed ? what do you guys recommend for my 16 in ??

The only safe way to do it is weigh each end of each axle. Then use the tire maker's chart to inflate to your load or maybe 5-10 lbs above it. Absent a tire makers chart, a Tire Guide will be next best. BTW, inflate all wheels on an axle to match the required pressure for the most heavily-loaded wheel.

Also, your wheels are marked for max pressure.

quote:

the tires state 65 psi cold on the sidewall for single & dual .

What is the exact wording there? Could it be so many pounds load at 65 psi?

quote:

the trans temp gauge is on my to do list .

Good idea. Aside from keeping you from shortening the life of the trans, it could keep you from burning down the MH.

A common cause of uphill gasser RV fires is an overheated trans bubbling fluid out the fill tube and onto an already hot exhaust system, which starts the fire.

I can't imagine why Barth did not put a trans cooler on mine. I have to use two humongous ones.

Our last Barth (she now owns Marvin+Doris) was a 1989 25’ Regal with the shorter P-30 chassis with 16” wheels and 454 engine. The data tag showed front GAWR as 4880 lbs, limited by the tire capacity at 65 psi, and rear GAWR as 7500 lbs, limited by the suspension because the tires could handle up to 8560 lbs. That’s a total of 12,380 for GVWR. We towed a 2800 lb VW Cabrio on a dolly with inertia brakes; can’t remember the dolly weight but do remember the total was within the GCWR. We put a lot of miles on the combination with no particular problems other than some slowing on the steeper grades. I had a GM spec sheet or booklet that had the GCWR’s for the 1988 P chassis; Marvin+Doris probably still have it. Barth provided the hitch, welded to the chassis. It had a 2” ball, and I’m sure it was a Class III.

It’s hard to imagine anyone replacing 19” wheels with 16”, even if the bolt holes lined up. The effect on speedometer, odometer and engine rpm for a given mph would be significant. It just doesn’t make sense. I agree with Doorman – Barth more than likely just “screwed up the data tag”. We purchased three different new coaches from them and spent a lot of time at the factory and in correspondence with them. They built great coaches, but their internal control systems were not particularly impressive. I could see where the wrong data could easily get onto a data tag.

Just as a side note, we tried stepping up to a 1989 28’ Regal that was built on the larger chassis with the 19” wheels. To quote my wife, “It rides like a truck.” We went right back to the 25’ with the smaller chassis and got the smooth ride were used to in our 1978 24’.

Bill Beard
Barth Owner Emeritus (three times)

quote:

Originally posted by Bill B:
Our last Barth (she now owns Marvin+Doris) was a 1989 25’ Regal with the shorter P-30 chassis with 16” wheels and 454 engine. The data tag showed front GAWR as 4880 lbs, limited by the tire capacity at 65 psi, and rear GAWR as 7500 lbs, limited by the suspension because the tires could handle up to 8560 lbs. That’s a total of 12,380 for GVWR. We towed a 2800 lb VW Cabrio on a dolly with inertia brakes; can’t remember the dolly weight but do remember the total was within the GCWR. We put a lot of miles on the combination with no particular problems other than some slowing on the steeper grades. I had a GM spec sheet or booklet that had the GCWR’s for the 1988 P chassis; Marvin+Doris probably still have it. Barth provided the hitch, welded to the chassis. It had a 2” ball, and I’m sure it was a Class III.

It’s hard to imagine anyone replacing 19” wheels with 16”, even if the bolt holes lined up. The effect on speedometer, odometer and engine rpm for a given mph would be significant. It just doesn’t make sense. I agree with Doorman – Barth more than likely just “screwed up the data tag”. We purchased three different new coaches from them and spent a lot of time at the factory and in correspondence with them. They built great coaches, but their internal control systems were not particularly impressive. I could see where the wrong data could easily get onto a data tag.

The GM tag would tell the tale.

quote:

Just as a side note, we tried stepping up to a 1989 28’ Regal that was built on the larger chassis with the 19” wheels. To quote my wife, “It rides like a truck.” We went right back to the 25’ with the smaller chassis and got the smooth ride were used to in our 1978 24’.

Bill Beard
Barth Owner Emeritus (three times)

We noticed the same thing, but liked the solid feel. The only time it jars us is on really bad hard-surfaced roads with potholes or sharp-edged bumps. It feels like Thor's hammer hit a frame rail. Of course, our tires are a little stiffer than normal, too.

quote:

What is the exact wording there? Could it be so many pounds load at 65 psi?

Bill h , you are exactly right , it states :
Max load single 1120 Kg ( 2470 lbs ) at 450 Kpd ( 65psi ) cold
Max load dual 975 Kg ( 2150 lbs ) at 450 Kpd ( 65 psi ) cold

So, should i run 65 psi all the time ?

Thanks, Bob

My apologies to all for posting the same thing twice – I posted the first one in a hurry and when I went back to check it, it wasn’t on the Forum. So I posted it again and then found out it had gone to page 2, which I hadn’t looked at. Rookie mistake.

Bob, It’s more and more probable that your chassis is the same one we had on our 1989 25’,the 159” P-Chassis with 16” wheels. Compare the VIN Nos. –

Yours: 1GBJP37W7G3316603 (1986 25’)
Ours: 1GBJP37W7J3336065 (1989 25’)
Ours: 1GBKP37W3J3314956 (1989 28’)

It looks like the four character “J” and the ninth “7” go with the short chassis and the “K” and the “3” go with the longer (178” wheelbase with the 19” wheels). (My GM manual that explained what the characters in the VIN mean went with our coach when we sold it, hence the guesswork.) The tenth character “G” and “J” are probably the year designation.

The 16” wheels came with 7.50R16LT tires and the loads you quoted are consistent with that. That size is no longer available, with the replacement being LT215/85R16 for which the loads are (from a Michelin load chart):

2335 lbs single, 2115 lbs dual at 65 psi
2180 lbs single, 1985 lbs dual at 60 psi
2055 lbs single, 1862 lbs dual at 55 psi
1940 lbs single, 1765 lbs dual at 50 psi

I don’t have a chart for the 7.50R16 and they’re hard (or impossible) to find any more.

Hopefully, there is a successfully attached PDF file of a column from the June, 1997, Motor Home magazine that is the best summary of tire inflation information that I’ve found. If you don’t have loaded vehicle weights on all four corners, you’re safe just going with the 65 psi max (plus 10 psi if you want the allowance for normal leakage).

So, bottom line answer to your question on the pressure to use is “yes”, but maybe some of the above info might be helpful to you.

Bill Beard
Barth Owner Emeritus (three times)

Bill you were close on vin #
1-nation of origin 1-us,2-canadian,3-mexican
2-manufacturers G- General Motors
3-make B-chevy incomplete
4- gvwr/brake J-10,000 -14,000, K 14,001-16,000
5-line and chassie-P-foward control
6-series 3-1 ton
7-body type, 7- motorhome
8- engine, W-7.4L V8 4BBL
9- check digit
10- year,G-1986
11 assembly plant, 3- Detroit, Mi
12-17 production sequence
Doorman

quote:

The 16” wheels came with 7.50R16LT tires That size is no longer available, with the replacement being LT215/85R16

I found the Michellin XPS Rib in 235/85R16 to be a good replacement steer tire for the no-longer-available 7.50R16's....a little more rubber on the road, plus a 700lb increase in capacity. The rear duals are more problematic, as the 235 has about an inch wider cross section than the 215 or the old 7.50's, and may have tire rub issues. To be safe, I'll probably go w/ the 215's when it's time to replace the rear 7.50's.

At the risk of starting a food fight, I'll just say that the Michellins have been very good to me....
30k miles over 7 years - almost undetectable tread wear and just the faintest hint of sidewall cracking that showed up this spring.......

quote:

As of yesterday the coach has 6 new tires all around. The "old" ones were the wrong size and the duals were touching. The tire dealer was very kind and replaced them.

The "old" ones were 235's, the new ones 215's.

(The quote is from Marvin+Doris in Barth Coaches Sold,10/30/2010.)

Moral: Don't use the 235's on the duals, but okay on the steers. Other considerations:

The 215's are basically the same diameter as the 7.50's but about 13% wider.
The 235's are about 4.6% larger in diameter than the 7.50's and about 23% wider.

What goes on the steers is strictly a personal preference.

Side note: Our 1978 24' came with bias ply tires. When we bought the '89, Jack Knotts was very proud to announce that Barth had finally switched to radials; they were Michelins and performed very well. Unfortunately, their 16" tires were no more resistant to aging than other tires.

Bill Beard
Barth Owner Emeritus (three times)

The 235s looked good the day they were put on, but somehow after we travelled a few miles and got home we tried to put the tire covers on and they touched. First thought was maybe they got low on pressure, but they were properly inflated and no water in the tanks (i.e. added weight). After the dealer exchanged them to 215s we have a smooth ride and no change in fuel mileage.
Regarding towing we have t admit our F150 pickup did not work out. We towed it with a 90 SOB (454 engine, 28 ft) from FL to Alaska and back with no problem and while the Barth did not lack power, we ran into the problem of the tail wagging the dog, making for an unpleasant wild ride at speeds over 45mph. Since we do not need to tow a car, we decided to do like Lenny and Judy, just rent a car if you need one at your destination. We hope to tow our boat though soon. Until then we got a carrier for firewood attached.

BTW with 25' you can go anywhere in the Barth anyway, if a dually pickup fits you will too. Except the drive thrus

When we first got the '89 25' Regal (now M+D's), we towed a VW Rabbit convertible with manual transmission, four on the ground. After we upgraded to a VW Cabriolet with auto transmission, we had to get a dolly for towing. When that VW was totalled by someone running a red light, we ended up with the Cabrio on the dolly. All three combinations towed with no handling problems, but M+D had a problem with their Ford 150 -- go figure. Maybe the Barth got so used to pulling German cars, it just took a dislke to the Ford.

Re 215's or 235's to replace the 7.50, another consideration is load rating. At 65 psi, single tire ratings are:

215 = 2335 lbs
7.50 = 2440 lbs
235 = 2623 lbs

Could be a reason to go 215's on the duals and 235's on the steers.

Bill Beard
Barth Owner Emeritus (three times)

quote:

Originally posted by Bill B:
All three combinations towed with no handling problems, but M+D had a problem with their Ford 150 -- go figure. Maybe the Barth got so used to pulling German cars, it just took a dislike to the Ford.

I wonder if it took a dislike to a heavier vehicle.

Also, every vehicle has slightly different front end geometry. A slight change in toe-in and/or caster can make a difference, too.

I have used a couple of bungees to center the steering wheel on at least one vehicle.

I would like to thank everyone for the reply's . you guys ( and gals) are AWSOME . this website & the people in it have a wealth of information .
This website is like a sheetz gas station motto . one stop for ALL your needs . no need to go anywhere else .
Thanks again , Bob