| Author |
Message |
Ed Jewett (Kristinsgrandpa) (65.134.220.75)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 02, 2003 - 7:36 pm: | |
I brought my bus shell home today to start the misery you have all gone through. My question is do you people with tag axles run the same air pressure in your tags as your drives. My shell is a 1988 Neoplan with a 40 ft. turning radius and it left black marks on the road where I backed in. I was expecting problems but didn't leave the blacktop once (a left hand backing turn an ess curve then a sharp left hand uphill backing turn all within 200 yds. It turns very sharp and could put a lot of wear on the tags by sliding them around like that. I have new Goodyears and don't want unnecessary wear. Also, I realize that Michelins are one of the top-of-the-line tires and would like to know how the Goodyears compare. Thanks a bunch. Later, Ed. |
DaveD (64.235.199.93)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 02, 2003 - 10:19 pm: | |
Bus companies usually move the tires as they wear out to the tag axles as this is where they get the most abuse. They do scrub somewhat on sharp turns.
DaveD |
abajaba (12.217.206.141)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 03, 2003 - 12:54 am: | |
When our 40 foot coaches make a sharp turn on concrete we leave black marks with our non-steering tag axles. The 45 foot J series MCI's probably do the same thing but I have not seen one where it was turned on concrete. Our lot at the garage is black top so I don't know how they work when they come out of the garage and turn sharp. Well it looks like black top. Maybe it's just black tire skid marks from years and years of turns? :-) |
Peter Broadribb (Madbrit) (216.67.221.46)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 03, 2003 - 1:06 am: | |
My '78 MCI-8 had a tag unloader switch. It was a togle switch by the driver's left arm and it reduced the pressure to the tag. It sounded an alarm all the time it was turned off.
I always used this feature when tight manouvering in or out of our yard.
Peter. |
Ed Jewett (Kristinsgrandpa) (65.134.220.127)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 03, 2003 - 9:30 am: | |
Thanks folks. Thanks for the unloader valve idea Peter. I helped put a 4 valve leveling system on a 4905 and it was easy, this shouldn't be a whole lot harder. Later,Ed. |
Stan (64.228.99.77)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 03, 2003 - 9:51 pm: | |
If you are running single tires on the tag axle you should have about 70% to 30% weight ratio between drive and tag axle. If you are adding a dump valve to the tag it is a little more work to add a pressure reducing valve (if you don't already have one) so that you can adjust the tag pressure for the right ratio. When your conversion is finished and ready for the road go to a scale that can weigh the axles separately and adjust the the tag pressure. Weight distribution in a coversion tends to be different than in a seated coach and too much pressure on the tag will cause excessive tire wear. |
Buswarrior (Buswarrior) (64.229.211.211)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 03, 2003 - 11:36 pm: | |
Hello Ed.
It has been common to run three different tire pressures on a 3 axle 40 footer. Highest in the front, lowest in the tag.
You need to check with the local tire distributor to check your tire manufacturer's recommendations for inflation for the intended weights on each axle/wheel position.
Each tire and manufacturer may have differences.
You want to carefully think about the tire pressure in the tag axle. If you run it unnecessarily hard, you will be stressing the tag axle components and promoting expensive damage by the pounding.
For a historical perspective, I am aware of an old time coach company that ran 100 lbs front, 85 lbs in the drives and 75lbs in the tags in their MC7 and 8 using the old Goodyear High Miler bias ply tires. This was back when no one was particularly thinking about fuel economy.
These days, the modern equipment is carrying more weight, running radial tires and running correspondingly higher tire pressures.
Tire scrub from the tag tires can be moderated somewhat with tire pressure: less air means more flex in the tire sidewall, and a little less marks. Commercial carriers ignored tire scrub as tag tires were a dumping ground for the trash off the other wheel positions. Unloading the tag on a 40 foot coach has little practical advantage to turning radius, but if you are concerned about leaving marks on your guest's driveway, everything helps a bit.
As for which manufacturer is "best", you have to consider a few things:
1) cost of tires - lots of spread between lowest and highest when you think about changing 8 tires.
2) wear vs. age - almost all of us will not wear out the tires, they will need replacing due to old age. It is popularly said that all bets are off once a commercial tire is older than 7 years. The rubber decays due to exposure to oxygen and sunlight. Can't hold back time. Some of us on here are running tires in perfectly good looking shape that are older than 7 years, (I will be replacing my 13 year old ones this year, only because I'm chicken, not because they look like they need it!) so good luck on deciding what YOU want to do!
3) retreads vs new casings vs used tires - contrary to popular belief, remanufactured tires are no more unreliable than a new tire, provided you are purchasing a reputable brand (ie Bandag) if you purchase a young casing, some savings are available when you factor in age vs wear. Your local tire distributor may also have good trade ins. Someone has replaced a set, and there is still more than enough good life left in a young tire casing for our low mileage purposes. Ask around, you might be surprised at the savings.
4) brand vs brand - Yup, Michelin is a lovely tire, but they are relatively expensive. Goodyear has a historically huge following in the bus industry. Bridgestone/Firestone are in there too. And the list gets bigger and bigger.
5) coach vs transit - Do NOT put cheaper transit tires on your highway going coach. Check the sidewall for speed limits. Many of the transit tires these days have either a 55mph/90kmh or 60mph/100kmh rating. This is not good enough for us. We need proper highway tires.
6) bus vs truck - no such thing. Tires come in sizes and weight ratings. Today's trucks and buses are running both the 22.5 and 24.5 sized rims, depending on the manufacturer. Historically, some refer to the 24.5 as truck wheels, and the 22.5 as bus wheels. Pick the proper tires for your coach, your rims and its rated weight. If you care, be sure to pay attention to the revolutions per mile for the tire. You may slightly improve your hill climbing, your fuel mileage or your top speed depending on whether you turn more or less revolutions than your current tires.
7) under what road and weather conditions will you be driving? - do you need a more aggressive drive axle tread, or put the same tire all around? Sand, mud or a damp grass campground can be worse than snow for getting a coach to move off, but a more aggressive tire makes more road noise. As usual, there's no free lunch!
If you have to be home for work on Monday morning and it starts raining/snowing Sunday morning while you are still 500 miles from home, then you better be happy with your tire purchase. If you are retired and don't plan on even moving unless the sun is shining, then does it really matter?
happy coaching!
buswarrior |
Johnny (67.241.224.54)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 05, 2003 - 4:39 pm: | |
Buswarrior makes some VERY good points.
First, a legal issue: retreads are NOT ALLOWED ON THE FRONT AXLE OF ANY BUS! However, they are perfectly legal (and often used) on drive & tag axles.
Second, highway-rib tires have almost-zero traction on anything more slippery than hard-pack dirt or gravel--wet grass, loose dirt, light mud, even semi-packed sand will get you stuck (been there, done that). For my schoolie, this is my plan: I will run siped highway rib tires on the steer axle, for obvious reasons. The drives will get what I can best call an all-season tread (not a rib, but not really a traction tire, either) on the outer duals, & a medium-agressive traction tire on the inner duals. This will prevent the extremely-embarassing (and potentially very expensive) situation of being stuck on wet grass on a level area, while avoiding the rougher ride & loud racket of agressive traction tires. Right now, I have 11R22.5's in front & 265/75R22.5's (equal to a 10R22.5) in back (front rib, rear all-season), but will probably run 11's all-around when completed. Yes, I do plan to run Bandag recaps on the drives.
While I know 11R22.5's are probably drastic overkill for my <26,000lb vehicle, I chose the size because they're available ANYWHERE (used by 99% of OTR trucks & many MDT's), consequently they're cheap, used carcasses for recapping are almost free (in fact, some places actually WILL give them to you), and a blowout in West Of Nowhere, Utah shouldn't require a 3-day wait for my oddball to arrive at a premium price--I can probably just grab a used tire at a big-truck junkyard. While I might have to live with a design I'm not thrilled with (like a traction on the steer, or a rib on the drive, or whatever), I can at least finish my trip & get home to get the right tire. Also, I strongly suggest carrying a spare, and the tools to change it if possible (I will!). |
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