You are a hot prospect for a trailer, Michael.
You have too much stuff.:p
:DJIM
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You are a hot prospect for a trailer, Michael.
You have too much stuff.:p
:DJIM
Also, keep in mind that Michelin has two different weight charts, one used for trucks and one used for RV's.
The weight ratings are actually the same, except that the truck chart lists total axle weights where the RV chart uses "corner" weights.
I guess they figure RV drivers are more likely to have each tire (or pair of duals) weighed as opposed to truckers who usually only have axle weight information from truck scales. I would also guess that most trucks are more evenly loaded that the typical bus used as an RV.
If you have individual weights for your front tires, take the highest weight and use it for your pressure settings on both sides. The same applies to the rest of the axles.
From Tom's post I just remembered the golf cart in the bay.
Start your weight reduction program there. Lose it.
Prevost and the converters are usually way too nice when they are put in the middle by customers that want everything but the kitchen sink in these buses, but the reality is they are built to a certain set of limitations and yours is one that exceeds those.
Every component is sized to handle the limits. Everything from brake surface area to air bag size to bearing capacity to wheels and to tires. Apart from the obvious revenue source most states have scales to keep truckers at or below their weight limits for the safety of the trucker and the other drivers on the road. Our buses are lousy when it comes to stopping and every pound makes a bad situation worse. When within the limits it takes us almost 3 times as long to stop from a given speed as a car traveling the same speed. Some car that gets rearended may have the golf cart to thank for that and the lawyer representing the family in the lawsuit may have the golf cart to thank for his contingency fee.
Okay - Using the axle weights from the weigh ticket, here's what I come up with. I'm asking you guys who actually know and understand this stuff to tell me if I'm on the right track to solving this issue.
- Steer axle weight = 15,340 lbs - divided by 2 yields 7,670 lbs at each tire
- Drive axle weight = 19,580 - divided by 4 yields 4,895 lbs at each tire
- Tag axle weight = 15,060 - divided by 2 yields 7,530 lbs at each tire
Now, on Firestone's inflation table for my FS400 tires - Firestone Truck Tire Inflation Tables, I get the following approximate values:
- Steer tire inflation closest match is 7.610 lbs = 120 psi recommended
- Drive tire inflation closest match is (Dual) 5,675 lbs at 80 psi recommended (that is the lowest weight on chart)
- Tag tire inflation closest match is (Single) 7,610 lbs at 120 psi
Something doesn't seem right on the drive axle conversion. It has four tires, of course, but am I correct in dividing the drive axle weight from the weigh ticket by four to get the approximate load per tire to find the correct approximate weight on each tire to look up the recommended psi on the load table/inflation chart?
I promise to have Vita read your responses to insure comprehension! (Brain damage ain't for the weak!) :rolleyes:
Michael,
Here it is what you need, and it is not far from you ;)
http://cgi.ebay.com/ebaymotors/09-MO...orsQ5fTrailers
http://cgi.ebay.com/ebaymotors/2005-...orsQ5fTrailers
Alek
Michael, now you are pulling our chain. Are you suggesting the drivers of entertainer coaches did not have to air up their tires?
Jim C is also pulling your chain. If you get a trailer we all know you will fill the trailer and your bays and the problem you have now will just get worse.
My shifter lever problem was caused by water getting by my driver side window during washing. It killed the whole shifter pad unit. I was able to get a re-built unit through the Detroit Diesel shop in West Sacramento Parts. They got it from Minn. or Wisc. Sorry I did not get their source. It saved me a lot of $$ over the $600,00 new price. Our present bus has a tighter fitting window.
Hi Michael. Regarding tire inflation, I keep mine above the recommended charts. I use the Michelin chart.
http://www.michelinrvtires.com/miche...ion-tables.jsp
Gary - I get the whole "inflating a few lbs more than the chart" thing - makes sense. I'm still struggling with making sure I'm reading the charts right and how to compare my axle weight numbers from the weigh ticket to make sure I'm comparing "apples to apples" (dividing axle weight numbers by 2 or 4 depending on which axle to get indivual tire weight numbers?).
Also, I'm going to take Steve Bennett's recommendation and get the bus re-weighed at a different scale on the way home tomorrow to validate the weight numbers I have now. I'll do it in two passes - once by individual axle and next weighing the bus in total.
Michael,
Divide your scale weights by 2 per axle, then use the dual numbers for the drive and single numbers for the tag and steer. Here's an example:
Steer - 15,340/2=7,670 Use the single weight from tire chart
Drive - 19,580/2=9,790 Use the dual weight from the tire chart
Tag - 15,060/2=7,530 Use the single weight from the tire chart
I know nothing about Firestones, but be sure your not exceeding the tire pressures for the weight. Look at the max pressure numbers on the tires. Also remember, your tire pressures are going to really increase when they get hot, so it's important that you don't put in too much air when cold.
On your way home, stop at exit 306 and re-weigh at the Q-T Truckstop. If they're not busy, you can weigh each wheel position by moving off the scale with each side of the bus. The concrete apron is wide enough to weigh one side then circle around and weigh the other side. Make sure someone is outside helping so your sure to split the axles evenly and not get bad readings. On any of the scales, you can screw up and not get the axles split evenly on each independent scale platform. Also, are you sure your toad didn't end up on your tag axle scale ticket? Always unhook the toad.
Tom - thanks for spelling it out for me! By George, I think I've got it! (finally!!!) I intend to follow your instructions to the letter tomorrow on the way home and will post the results tomorrow night after we get home.
Divide your weight by two not four on the drive wheels. So ,if you overall weight on the drive is say 19500 lbs, you would look for 8750 lbs on the chart under duals. If you read the instructions at the top, it indicates weighing each tire individually. If say one of the front tires weighs more than the other on the front, use the heavier weight for air pressure on using the chart.
Just my two cents on getting the wieght for eaxh axle. I use a truck scale at a local farmers COOP store that has a flat approch and exit. I put the front axle on the scale, record the wieght then move forward so the drives are also on the scale and record the wieght of the two axles. Last I put all the axles on the scale. This gives the total wieght. Then do the math to detremine the wieght of each axle. I think using a scale with a flat approach and exit is very important. Ever notice when stopped on a less than level spot how the tires on the low side of the coach willl look low on pressure due to the additional load cause by the coach not being level.
Forgot to say. My 99 XLV chassis has a Prevost weight and inflation plate on the inside of the rear engine door on the passenger side.
Larry et al,
The inflation pressures recommended by Prevost or the converter are at best starting points until you can get your coach weighed with all your stuff on board.
The only correct way to learn inflation pressures is to get your coach weighed with full fuel, full water, all your normal stuff on board.
A little caution here. IN looking at both the Firestone tables, and the Michelin tables, they are reported differently.
The Firestone tables (which match the tires that Michael has) give weights per wheel, even under the used as a dual section.
The Michelin tables, however don't, and the weights are listed for both tires combined as a dual axle. So, Tom and Gary's suggestion works fine if you're looking at the Michelin tables. If you're looking at the Firestone tables, a divide by 4 is needed.
Ray
I stopped at the QT Truck Stop at exit 306 on the way home, as recommended by Tom to have the bus reweighed with the toad unhooked. for more accuracy, I filled my fresh water tank before leaving Chattanooga this morning and topped off the fuel tanks at the QT before weighing. Vita went inside and explained to the "Weigh Master" what we were trying to accomplish. He understood exactly what we were trying to do, but unfortunately, the CAT scales have a metal framework over them that holds up the CAT Scale sign and the intercom box that allows the driver to talk to the Weigh Master. The frame is very close to the edge of the scale pads and prevents you from weighing one side or tire position at a time. Also, he said that because of the way the bus axles are configured that the Cat Scales are not set up to give accurate separate weights per axle on the drive and steer axles (the steer and tag axles are too close together). He recommended weighing the bus in total and the weigh ticket would reflect a separate weight for the steer axle and the combined weight of the drive and tag axles. He then said to take our weight ticket from Saturday from the Pilot Truckstop and subtract the drive axle weight on the Pilot ticket from the combined weight on the QT ticket to get the actual tag axle weight.
Here's the good news: on the QT scales, with full fuel, full fresh water, golf cart in the front bay, approximately 600 lbs of human cargo (two teen girls asleep in the back and one overweight driver - Vita was outside directing me onto the scales), two small Shih Tzu dogs weighing a total of 18 lbs, and various and sundry clothes, food, toiletries and personal electronic gadgets - the bus weighed a total of 47, 060 (only 60 lbs over the data plate GVWR numbers)!
The steer axle was 15,220 lbs.
The combined drive and tag axles were 31,840 lbs.
Total Gross Weight was 47,060 lbs.
Now, if I do what the Weigh Master suggested and subtract the drive axle weight from the combined drive/tag weight, (31,840 - 19,580), I get 12,260 lbs. for the tag axle! This is much closer in line with whats on the data plate!
Data Plate numbers:
•Steer axle - 14,600 lbs
•Drive axle - 20,400 lbs
•Tag axle - 12,000 lbs
•Gross weight - 47,000 lbs
Now, all I've got to do is make sure that my actual tire inflation is the correct psi for what the chart recommends! Whoopee! :D
As far as the weight difference from Saturday to Monday - all I can figure is the the toad somehow was on the scale pad at the Pilot scales and got included in the weight. :confused:
I'm not sure I understand. This time you weighed the tag and drives combined, and you are subtracting the weight of the drives from previous weighing? I'm not sure I would do that. I guess it's a pretty good estimate, but.
When I've weighed at these CAT scales, I've been able to split the drive and tag onto separate parts of the scale. Obviously this is prone to some degree of error as it's really hard to get this situated so that you get an accurate weight.
But, I'm glad your overall weight came down.
Ray - I don't know what to say/do. We're just doing what the Weigh Master at the CAT Scale said. He did say that, the way we weighed at the Pilot probably included the weight of the toad with the rear most (tag) axle, so assuming ( yeah, I know about "assuming"...) that the other axle weights at Pilot were essentially accurate, subtracting the drive axle weight from the Pilot ticket from the combined steer/tag weight on the QT ticket should give a good estimate of the actual tag axle weight. :confused: It made sense when Vita explained what he said! Since the steer axle weight was only 120 lbs difference between the two scale tickets, it seemed like a reasonable way to get a close estimate of the other two axles....
Yeah, I understand. I was just concerned that the whole previous weighing was a bit busted, especially at the read end, affecting certainly the tag, but possibly the drives too?
Best would be if you could get a real weight of both your tag and drive axles, however, I would guess that gives you a pretty good approximation at the moment.
Generally, most of us tend to be overweight on the steers, so that part is critical.
I also tried to weigh mine with the toad attached on CAT scales the first time. It was obvious from the weights that it didn't work and I got the toad weight on the ticket also.
Pulled around, dumped the toad, pulled back on the scales. They should be able to let you know if you aren't spotted properly for getting your drive and tag weighed separately - the scales are designed for that.
If each wheel is weighed separately like we did at Spearfish, is any allowance made for some of weight being duplicated?
Michael,
The weigh master is a fuel clerk and he's full of ca ca! I've weighed there since they opened, side to side, front to rear, with toad, without toad and the numbers were close to other scales I used. I do this 2 or 3 times a year just to check on the crap I'm carrying. If you go back there, call me, I'm 15 miles away and I guarantee you it will work. I have tickets in the bus right now that show side to side numbers from that scale.
You may be OK now on your gross, but the steer is still overloaded.
Ray - Good catch, I didn't look at the chart, but the end result for the duals are the same? You have to mentally divide the Michelin numbers by 2.
I didn't compare side by side, but I assume the end result numbers are very close. It was just interesting when I looked at one chart, and the numbers went up to somewhere about 18,000, while the other only went up to 9,000 pounds!Quote:
Ray - Good catch, I didn't look at the chart, but the end result for the duals are the same? You have to mentally divide the Michelin numbers by 2.
At Spearfish my drive axle weighed 10,100 on one side and 9300 on the other.
Add together and divide by 2 and you get 9700 and the michelin chart only goes down to 11680 at 85 lbs. Based on the chart I should have about 70 lbs in the drive tires.WHAT AM I DOING WRONG??
I think that it's fairly common that the drives are lightly loaded. If 85# is the lowest on the scale, then that's the minimum I would run. Personally, I would probably bump it a bit to 90 or 95 pounds. I don't think you can hurt anything at those values.
In looking at my last weights, mine too is off the charts at the bottom end. I'm running 100 pounds in mine, instead of 85.
ray
Tom - I'll have to have you show me how to weigh one side at a time on that scale. That sign frame is almost right up against the scale platforms a little forward of the halfway point of the platforms and doesn't seem to leave any room to maneuver one side off the scale. Since you've done it before, I'm sure I'm missing something, but I sure don't see how it's done! :confused:
The charts show recommended minimum PSI. Also, the max is 130 lbs.
I keep my front 365's at 110 lbs, my 315 drive at 105, & 315 tags at 100.
I wouldn't feel comfortable at much less besides I wan to optimize my mileage.
I sent the following inquiry to Firestone a couple of days ago:
Today, I got the following reply:Quote:
I've just had a new set of Firestone FS 400 tires installed on my 1996 Prevost XLV conversion bus (45 feet long) and am trying to determine the correct tire pressure at each axle end to insure safety and long wear. I'm confused about how to use the inflation tables and need guidance. I've had the bus weighed and have a weigh ticket that gives me the weight on each axle (steer, drive, tag). To match up with the inflation charts, do I divide the weigh ticket numbers by 2 for the steer axle, by 4 for the drive axle (duals), and by 2 for the tag axle to find the correct recommended psi on the chart? When I divide as stated above, I find that the individual derived tire position weight numbers for the drive axle are below the lowest number on the chart, which makes me think I'm doing something wrong. Please help! Thank you, Michael Terry
What do you guys/gals think of what Mr. Hayn suggests?Quote:
Michael,
You are using the right method to determining the individual tire loads from the weight data.
As you already know, the tables represent a maximum load at several minimum inflation pressures.
The table does not extend below 80 psi because this represents a minimum inflation pressure no matter how lightly loaded you are.
However, for your Prevost I would recommend that you maintain 100 psi in your steer tires and 90psi in your drive and tag axle tires.
Michael Hayn
Engineering Manager
OE Truck/Bus Tire Accounts
Bridgestone Americas Tire Operations LLC
535 Marriott Drive
Nashville, TN 37214
615-937-3460 office
615-584-4711 cell
haynmichael@bfusa.com
Hi Michael. Yes. Although, I keep about 105 in my drives and 110 in my front
365's.
Mike: As an example my 45 Ft. Liberty weights are as follows:
Total Weight 47,450 Lbs.
Left Front 7500#------ Required Air Psi. 115 #
Right Front 7600# -----Required Air Psi. 115 #
Left Drivers 10,050#---Req.uired Air Psi. 100 #
Right Drivers 9100#----Required Air Psi. 100 #
Left Tag 6500 # -------Req.Air Psi. 90 #
Right Tag 6100 # ------Req.Air Psi. 90 #
Tags up Drivers # 15,700#
These weights were aquired using individual scales placed under each tire location courtesy of Weights & Measure personel S, Dakota State at one of our POG Ralley's in Spearfish, SD.
Best to use your own coach weights. Under Inflation causes heat and tire failure.
Safe Travels to you.
That matches completely with what was suggested in previous posts. As I've mentioned, generally our drive wheels are lightly loaded (at least on a non-slide) coach given the load carrying capacity of the 4 wheels.
I ran 100 pounds in mine, even though mine, like yours, are off the bottom of the chart.
I run 115, 100, 95 in mine.
ray
I found this info this morning by searching Prevost's Online tech manuals in the "Wheels, Hubs, & Tires" section:
13.1 Recommended Tire Inflation Pressure (Cold)
Inflation pressure should be checked when tires are cold. Driving, even for a short distance, will cause the tire to warm up and the air pressure to
increase. Check inflation pressure on all tires using an accurate tire gauge.
The maximum loading tire inflation pressure (cold) for 12 R 22.5 tires are as follows:
Front axle....................................115 psi (792 kPa)
Drive axle......................................90 psi (620 kPa)
Tag axle ........................................95 psi (655 kPa)
Note: It is recommended that all tires on coach be of the same type.
Note: Tires are considered cold when the vehicle has not been driven for at least three hours, or driven less than 1 mile (1,6 km).
Driving, even for a short distance, causes tires to heat up and air pressure to increase.
Note: Never bleed air from hot tires as tires will then be underinflated. Use an accurate tire gauge to check pressures. (Do not kick tires as an inflation check. This is an unreliable method).
Caution: In the case of a converted vehicle, weigh vehicle fully loaded and pressurize according to tire manufacturer's recommendations.
Caution: These tire pressures are established in accordance with the maximum allowable load on each axle. A lower pressure is recommended if the axle load is less than the above specifications.
My tires are 315/80R22.5, so I guess the following would apply?:
RECOMMENDED TIRE INFLATION PRESSURE AT MAXIMUM LOAD (cold)
Tires 315/80R22.5
Front axle.............................................. .................................................. ............................100 psi (689 kPa)
Drive axle.............................................. .................................................. ..............................90 psi (620 kPa)
tag axle .................................................. .................................................. .............................80 psi (551 kPa)
Spare tire (if applicable)....................................... .................................................. ..............100 psi (689 kPa)
Caution: In the case of a converted vehicle, weigh it fully loaded and pressurize according to tire manufacturer's recommendations.
My guy at Apalachee RV reviewed all the information so far and recommends 120 psi in the steers and 110 psi on both the drives and the tags.
So many options, so many ways to screw this up! :confused:
Where are you getting those numbers?
Your front weights were 15,200 if I remember correctly. In the Firestore tables, that's a minimum of 110 pounds. Where in the world are you getting 100 pounds for your steers?
Here is the values for your tires.
Attachment 6018
I don't see where you are getting 100 pounds for your steers, if you are weighing in at 15,200? I see 110 pounds.
And as the Firestone guy said, I personally wouldn't run 90 pounds on your drives, I would bump it to 100. That's just my personal opinion. Obviously, that's not required, but allows you some extra carrying capacity.
Ray
Tire pressure is a case where more is definitely better from a safety perspective
I'm zipping up my flame proof suit so feel free to respond.
Do you think if it is this hard to figure out how much air to put in your tires you should be driving one of these buses? Especially considering that is something that should have been on the to-do list for the first pre-trip inspection.
Seeing all these posts, especially with the diverse opinions leads me to believe that if I asked if everyone is doing the pre-trip brake inspections I would be getting the "deer in the headlights" look.
Come on guys.
Ray - "where I got those numbers" was from Prevost's online technical manuals in the "Wheels, Hubs, & Tires" section. I wasn't saying that they were appropriate for my/our application - in fact, the reason I posted that info was to highlight the wide range of inflation/load numbers out there which add to the confusion of "what's right" for idiots like me!
At any rate, tomorrow I'm going to adjust the steers to 115 psi and the drives & tags to 100 psi. After reviewing all the diverse specs, suggestions, recommendations, and opinions - those are the numbers that make the most sense to me. I'm now realizing that I way over analyzed this and turned what should have been a simple process into a royal cluster f%#k! :o
I realize that I'm driving you guys crazy with idiot questions and for that I apologize. The problem is that, since my accident my lack of mobility/dexterity prevents me from digging in and figuring out stuff that I would have figured on my own in my former life. It often leaves me to "depend on the kindness of strangers" these days. The good news is - I do eventually learn and retain what I'm taught (or take damned good notes)!
Also, while at the bus tomorrow, I'm going to pull the shift pad module out of its frame and see if I can clean the pad contacts on the back to resolve my shifter issue. W.W. Williams has obtained a new shifter module from Alabama and will install it for me, but the parts are over $1,300 and with labor/time/etc the bill will be over $2,000. The other option is a "shifter repair kit" that they can get for about $100 from the Greer, SC location, but after labor, tax, tag, & freight - that option would be almost $800 and the tech said he can't guarantee that the repair kit would resolve my issue. (We wouldn't know until after they "installed" it and then I would have "bought" it and might still have an inoperable shifter) Soooo... before I "jump off the cliff" with one of the expensive options, I figure I've got nothing to lose by seeing if it's as simple as a dirty or corroded contact on the pad. We'll see.... :rolleyes:
Sorry guys.... :o