| Author | Message | ||
| L James Jones Jr (Jamo)
Registered Member Username: Jamo Post Number: 34 Registered: 11-2007 Posted From: 24.59.119.14  Rating: N/A |
I was checking my tire pressures this afternoon (12R22.5), and after sitting most of the winter, they're all between 90-95. As per the casings, I can go as high as 120#, and it also says not to exceed 55mph. Huh....?? What do you guys normally run on the front & rear pressures? I'd rather get better mileage, better wear, and a stiffer ride is OK with me. Is closer to 120# better?? Thanks Folks.........Jamo | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 595 Registered: 11-2005 Posted From: 208.54.200.243  Rating: N/A |
James, I run 90 in front and 100 in the rear of my 4104. I figure this is a compromise between ride and wear. However, I have 1100R x 22.5 16 Ply. The 4104 is not a heavy bus and, in my opinion, doesn't need high tire pressures. | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 309 Registered: 10-2004 Posted From: 71.59.75.212 Rating: N/A |
I ran 90 all around in my 04....but I was going for ride. I doubt you will realize any savings MPG wise with typical conversion useage so I'd go comfort 55mph Max.....ture was intended for transit use. if you continue to use them I would suggest regular (hourly) stops to let them cool. They do have a high probability of coming apart when overheated | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 230 Registered: 7-2006 Posted From: 4.240.214.157 Rating: N/A |
RJL...best check in here... your words of wisdom, please!  Thanx RCB | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 310 Registered: 10-2004 Posted From: 71.59.75.212 Rating: N/A |
rj's on vacation | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 311 Registered: 10-2004 Posted From: 71.59.75.212 Rating: N/A |
I'll guess on RJ's comments. 1. go weigh your bus by axle 2. Go to your tire manufactures website and get the inflation chart 3. Fill to that pressure 4. make a bit harder if you want 0.1% better MPG | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 142 Registered: 3-2006 Posted From: 209.50.74.55 Rating: N/A |
Buswarrior Chime in here about 55mph tires. Remember we used to run them on the GM's in transit service. They will overheat and come apart on the highway with high speed use. They were not built for sustained highway use. Bill | ||
| L James Jones Jr (Jamo)
Registered Member Username: Jamo Post Number: 35 Registered: 11-2007 Posted From: 24.59.119.14 Rating: N/A |
You guys think my 4104 is capable of "high speed use"?? If I stay around 55-60 mph?? We didn't buy the bus to make high speed runs, just to zig zag around where ever and when ever we see a need to deviate from our informal destination. That's how we ride when we travel by Harley too...no set plan, no set ETA. Guess I'll have to check all the tires for this "55 mph" thing. I just happened to notice it on one as I was looking over my rubber. With all these scary posts about runaway engines, dangerous voltages, messed up racks & governors, and now unsafe tires...I just might have to trade my rig for a bean bag chair and a wide screen TV...........................NOT! Thanks.........Jamo | ||
| JC Alacoque (Jc_alacoque)
Registered Member Username: Jc_alacoque Post Number: 62 Registered: 7-2006 Posted From: 72.45.68.242 Rating: N/A |
I run mine at 80 lbs. That's 10 more than the inflation chart recommends after weighting the coach. It sure is nicer than the previous owner's 100 psi when I first got it. I run the hockey team's 102D3 at 105, 85 and 75 psi front to back, per the MCI manual. Better than the previous maintenance guy's 100 all around. That's what the tire shops will do if you let them. Weigh your coach, each axle. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1209 Registered: 12-2000 Posted From: 76.68.120.241  Rating: N/A |
Hello Jamo. Sounds like you have tires that were cooked up for transit use. (Everyone else, what are YOUR tires rated for top speed? Just because it isn't on the sidewall, doesn't make it an 80 mph runner, many, many tires are rated for 65...) Anyhoo, Branded with a 55 mph top speed, and in their construction, depending on manufacturer and model, thicker sidewalls, different construction techniques, different tread patterns and rubber compounding for durable lower speed transit service. It is generally felt that these tires should not be used for sustained highway use. The transit tires run hotter, (more material in the sidewall to flex, other construction influences) and will fail sooner, according to ambient temp and speed operated at, than a tire that has been constructed for sustained highway use. End of the world? Well, as you indicate, you aren't a high miler, preferring to wander the roads less travelled. With heat the big threat in these tires, the ambient temp is your biggest challenge. The hotter it is outside, the harder it will be for the tires to shed heat, the more likely they will be to fail. Weight plays a big factor, whether your coach will be closing on the tires' ratings closes the margin for you to play in. Every busnut should have one of those infrared temperature guns. Besides all the other good things (bearings, brake drums, radiators, etc) use yours to keep a closer eye on tire temperatures just after you pull off the highway. Compare your temps to other busnuts with similar equipment, and of course, the tire manufacturer reps should be able to advise as to how high you don't want to see, preferably in a written document of some sort, talk is cheap. On the administrative trouble side, those few keener enforcement types are aware of these "strange tires" and dream of finding someone running them faster than the sidewall warning. Hard to do from a scale house, but it isn't as big a secret to them as it is to the rest of the world. Tire legislation in many jurisdictions is not tied to the commercial regulations, it is written to apply to everything on the road. As for tire pressures, set them according to the tire manufacturer's inflation chart based on the operating weight of the coach. Higher than that, beats the crap out of your bus, the tire won't be sitting on the road properly, may lead to wander in the steering, lower than recommended makes excessive heat in sidewall flex, and we know where that will lead. Like any tire, regularly watch the tire pressures, inspect for signs of age and damage, check running temperatures, treat it the way mother (the manufacturer) intended for it to be treated, and you can successfully run them. See how this thread pans out, check with the manufacturer, and makes your choices. happy coaching! buswarrior | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1210 Registered: 12-2000 Posted From: 76.68.120.241 Rating: N/A |
Oh, and the history part... There was a day, not as long ago as some of us would like... There were REAL transit tires that were rated for 35 mph. Bias ply, compounded as hard as a rock, slid in the rain like you were running on oil... slid on dry pavement like you were running on water.... You absolutely did NOT get out on the highway with those ones. Can you imagine how cheap their construction must have been? The cops were always watching the special service buses that were run to the horse track on the outskirts...before the lotteries, those buses went out groaning... That set of buses were outfitted with the more expensive "highway tires" the cops knew to watch for odd unit numbers and checked them specifically. Ah, those were the days... NOT! Thank God for heavy radial tires and the continuing work of the engineers at the tire companies to create better and better rubber compounds! The young ones don't have a clue, as they wheel around corners, driving with one hand, other on the cell, heeled over with the baggage doors scraping the road. Try that with the old Goodyear High Milers... happy coaching! buswarrior | ||
| hiwaycallin (Hiwaycallin)
Registered Member Username: Hiwaycallin Post Number: 10 Registered: 10-2007 Posted From: 208.98.218.205 Rating: N/A |
Buswarrior, you're a walking encyclopedia. You should write a book. It's a rare gift to have the combination of such knowledge with the ability to share it in the most interesting and memorable way. | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 20 Registered: 11-2007 Posted From: 124.186.158.142 Rating: N/A |
Tyre shops only know about one pressure - 100psi all around.Saves them from having to think. Correct pressures for my MC8 are way under that - more like 80 to 85 and even lower for the tag. OP said "I'd rather get better mileage, better wear, and a stiffer ride is OK with me." I consider the job of the tyres is not to keep me rich by lasting forever, it is to keep me alive by stopping when I need to stop and keeping the bus on the road. A soft ride is nice too. Overinflated tyres do none of these 3 essential things. (Message edited by t_lee on February 26, 2008) | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 143 Registered: 3-2006 Posted From: 209.50.74.37 Rating: N/A |
Buswarrior I knew you would let us all know the pitfalls of these low speed tires. Yes. I remember the days of flying down the highway in a 6V71 / VH9 GMC doing 52 mph top speed with the pedal pushed through the floor. The passengers shuffling around because they thought you would miss the first race. Sometimes you did then listen to the comments. The good old days. Too bad you weren't around then Buswarrior. Your too young to remember that. Bill | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 597 Registered: 11-2005 Posted From: 208.54.200.157 Rating: N/A |
James, I had a good laugh at the post about high speed driving. If I wanted high speed I would never have gotten a 4104 which strains to top 60. However, like you, I'm in no rush. We are tourists not land speed record seekers. My bus systems are about as simple as one could be and I plan to keep it that way. Not an automatic gadget anywhere. Before I changed to radials I ran 75psi all around but had to increase pressures in the radials because they are so bouncy, especially at lower speeds. I'm giving serious thought to decreasing the rears to 85psi because it doesn't bounce as much as the front. A 4104 is so light compared to others that you can probably easily run 80. Of course none of this may apply to your transit tires. I run TOYO M122 11R22.5 14 ply which are common all position truck tires. | ||
| L James Jones Jr (Jamo)
Registered Member Username: Jamo Post Number: 36 Registered: 11-2007 Posted From: 24.59.119.14 Rating: N/A |
Thanks for all the replies. I was more concerned with ruining my tires by running too low on pressures. I didn't realize I had so much room to tweak them. As for the "55 mph" tire, it might only be the one, I never checked the rest. 'Course it is on the front end... Once spring hits, I'll weigh the bus at each end & then be back with another "high pressure" question if need be. Until then, I'm just going to keep digging my sorry ass out of all this snow. Maybe I should update my pic...I could make BusWarrior look like a wuss with the snowload. I'll bet you have more on yours too though....eh?? Thanks again....gotta love this site. ~Jamo | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1170 Registered: 5-2001 Posted From: 65.74.66.116 Rating: N/A |
Fellas, it may be that some transit tires do run warmer than highway tires. I was concerned about that when I put on a Toyo tire with that 55 mph embossed on its side. However, I have been using one of those infrared thermometers for some time, and that tire runs more than 10 degrees F COOLER than any of the Goodyear highway tires on the rest of the coach. Then, I got to thinking about the other ratings on the tire. It's rated for 9000 lbs as a single at 130 psi cold inflation pressure. Since all the Goodyears are only rated into the 7000 lb. range, I realized that it would be easy to overheat one of those Goodyears at 9000 lbs. IF I ran it at 75 mph. One of the easiest ways to keep temperatures down in any given case is to slow down. If I had to run a tire overloaded for a short distance, driving slowly is about the safest thing I could do, short of not driving at all. That very problem cropped up in the southern Yukon this last summer. We blew a rear coming out of a construction zone, but all the tires were cool when we pulled over to check for the damage. We were still well over ten miles from Fort Nelson. I decided that we could limp into town to get a replacement tire if we went slow enough. With a few checks to see if the remaining dual was getting too warm, we found that 35 mph was no problem at all. What all this means to me is that the 9000 lb rating on the 55 mph tire was the cause of it's low speed rating; its construction did not cause it to heat up at highway speed. And the fact that it ran cooler meant that it was using less energy. I think that the weight that those two axle transits were running, coupled with the speed limited gearing of the transits created a market for the tire manufacturers that required the prominent speed limited marking for tires that could serve that market. Anyway, if I get any more, I will be sure to check the temperature that they run before trusting them too far. You never know; I might find one that runs hotter. As for the one that we aready have, I don't lose any sleep over it because I am satisfied that there is no danger in using it. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 234 Registered: 10-2006 Posted From: 66.90.226.205 Rating: N/A |
"If I wanted high speed I would never have gotten a 4104 which strains to top 60." You need a tune up!! FF | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 21 Registered: 11-2007 Posted From: 60.229.13.132 Rating: N/A |
"Once spring hits, I'll weigh the bus at each end & then be back with another "high pressure" question if need be." Try to weigh each side of each axle individually if you can find a suitable weighbridge. Conventional wisdom is to pump both sides up to the pressure dictated by the heaviest side. That doesn't seem very logical to me as it would result in different rolling radii, but at least it will give you an idea of how balanced side to side it is. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 599 Registered: 11-2005 Posted From: 208.54.200.8 Rating: N/A |
Tomc, You will find that the front shaded tire runs coolest of all, other things normal. The inside duals will run the hottest, they seem to absorb engine and rear axle heat the most. Nothing surprising about that. Front and rear in direct sunlight in hot weather will be considerably hotter than the same tires on the shaded side. | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 88 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
Jim what was the ambient temp. outside when you checked pressure. If they are at 110 cold when it is 70degrees outside the cold pressures will be AT LEAST 10lbs less when it is 40degrees out. I run 100 they are 85 in winter sitting and build almost to 120 rolling on a hot summer day. We have pressure monitors and can watch them close. I do agree at the remarkable difference sun and shade have on pressures too. If the bus sits half in the sun when checking pressures the sunny side will give you incorrect readings and be a couple higher. On ours if the bus is sitting with the gen running I can watch the left inside duel rise as the exhaust pipe for the gen runs just inside of it. (Message edited by Joe Camper on February 28, 2008) |