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Author Topic: Goodyear Tires  (Read 6247 times)
Sean
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'85 Neoplan Spaceliner "Odyssey"


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« Reply #45 on: July 11, 2009, 10:27:38 AM »

...
I know that Sean has a wireless tire monitor that both transmits tire pressure and tire temperature.  Maybe Sean will share in the make of his monitor!


We have a SmarTire (http://www.smartire.com/rv), and we love it.  It's a bit pricey, and you really want to install it when you are changing or upgrading your tires, because the sensors actually mount inside the wheels (they are secured with a band clamp).  Also, you will want to watch like a hawk any time a tire is changed, to make sure the tire jockey is careful to avoid the sender with the tire irons.

My setup has two antennas -- one in front near the steer axle, and one in back near the drive axle.  There is a small display on the dashboard, and the display and antennas wire back to a small control box, which is also wired to switched 12-volt power.  If you have a toad, you may need a third antenna at the very back of the bus to pick up the toad senders, or you may be able to locate one antenna to pick up the toad and the rear wheels together.

I checked with my friend at Marathon he said they follow Prevost recommendations for air pressure they don't weigh the axles for air pressure. They just stay in the 51,400 lbs gross weight using 365/70R on the front, tag and 315/80R on the drives


One of Marathon's dirty secrets is that all their coaches are extra-legal weight.  If non-commercial RV's had to stop at weigh stations, every one of their slide-equipped coaches would be cited in most states (a handful of western states have very generous limits; ironically, Oregon, where Marathons are built, is not one of them).

Contrary to what your friend there suggests, Marathon figures the weight for each new model as it is completed.  However, they have not added a new model to their lineup in years.  They have 17 floor plans (each with a known weight, more or less), and you can get anything you want as long as it is one of those plans.  The days of truly custom Marathon conversions ended nearly a decade ago.

Also, I would not hold Marathon up as a paragon of safety or good design.  I've had to help clean up their mess more than once, and I wouldn't recommend a new Marathon to anyone even on a bet.  (However, some of their older coaches can be excellent values on the used market -- their design deficiencies are now well-known, and it is relatively easy to make one of their older units into a reliable and functional coach).  Among other things, their willful disregard for safety codes (including the federal bridge limit) troubles me.  Lastly, no one ever got sued for sticking with the chassis-builder's maximum recommendation.

... Over the years I have found out a bus equipped with a tag or boggie it it easy to over load the front axle about impossible to over load the rear and tags. ...


Hmm.  If I had a way to hang about 2,000 lbs on my front bumper I would, just to take some weight off my poor, overloaded drivers.  When I was designing my coach, I did everything I could to move weight forward, including putting 1,500 lbs of batteries, cables, and equipment over the front wheel wells.

Seated coaches tend to fill from the front -- that's what passengers, left to themselves, will do.  By contrast, conversions tend to be heavy in the rear, because that's where the partitions end up to divide off the bedroom and bathroom (and woodwork is heavy), plus many of the heavier fixtures such as sinks, showers, toilets, etc., not to mention the matress and bed platform.  The galley, another heavy part of the coach, while ahead of the drivers, generally is closer to them than the steers.

To some degree, you can compensate for this in the bays, by putting heavy stuff like generators and batteries forward.  Many of the S&S class-A builders are locating their gennys ahead of the front axle for just this reason.  Our weird bay configuration made this difficult for us.

Incidentally, the reason Prevost is equipping their conversion shells and some seated coaches with 10.5" rims for 365/70R22.5 tires is not really because the 315/80R22.5 on 9" rims can not handle the load -- they can.  It is for passenger comfort, to run lower tire pressures.  To carry the legal (federal) limit of 20,000 lbs on the steer axle, you would need to inflate your 315/80R tires to 130psi, which could be a bone-jarring ride (by Prevost standards, anyway).  Using the larger tires allows for much lower (thus more comfortable) air pressures.

FWIW, I tried this same technique on my own coach, by going from 12R22.5 tires to 315/80R22.5 tires, both of which will fit on my 9" rims (I upgraded from 8.25" to 9" when I switched to aluminum wheels, just so I could do this).  In our case, comfort was not the issue, but rather soft-surface traction (we spend a fair amount of time off the pavement), and we wanted to run the lower pressures.  Ultimately, we found it was not worth the hassle or expense.  The heavier tires are harder to find, much more expensive, and carry a higher FET.  We've now switched back to 12R22.5 all the way around.

-Sean
http://OurOdyssey.BlogSpot.com
« Last Edit: July 11, 2009, 11:01:36 AM by Sean » Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
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« Reply #46 on: July 11, 2009, 10:45:38 AM »

If, you want more weight on your front put more air on the tags, works on Prevost,Eagle and MCI I don't know about a Neo and yes the last 45 foot Eagles built in Brownsville had a air tag    good luck
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John316
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« Reply #47 on: July 11, 2009, 10:46:44 AM »

Sean,

Thanks for the post, and the info. It was helpful.

God bless,

John
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MCI 1995 DL3. DD S60 with a Allison B500.
Sean
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« Reply #48 on: July 11, 2009, 10:58:23 AM »

If, you want more weight on your front put more air on the tags, works on Prevost,Eagle and MCI I don't know about a Neo and yes the last 45 foot Eagles built in Brownsville had a air tag    good luck


If I had a way to do that, I would have done so long ago.  The tags are underloaded compared to the drivers.

Unfortunately, Neoplan uses a single ride-height valve in the back.  There is no separate control for the tag air, and no way to induce differential pressure in the tag bags versus the drive bags.  Putting a second ride height valve in would just cause the axles to constantly compete with each other.  About the only way to increase the percentage of weight on the tags is to go to a larger diameter air spring.  I've probably asked a dozen shops about this, and not a single one was willing to touch the project.

-Sean
http://OurOdyssey.BlogSpot.com
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Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
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