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Author Topic: Tire Size  (Read 10775 times)
gus
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« Reply #15 on: July 03, 2007, 08:27:48 PM »

My understanding is pretty much the same as Dallas'. The LP 24.5 replaces the regular 22.5 series 80 (Series 80 tires aren't marked as such because they were the standard for years, both for cars and trucks) and the two are roughly the same diameter.

The 75 in 295R 75 22.5 means the distance from the tread to the wheel is 75% of the max tire width.

The 295R7522.5 is very close to 12" max width, the 275R7522.5 is slightly more than 11".

 It does surprise me that Series 75s are considered LP because there isn't much difference between 75% and 80% (9.6" to 8.8"). I would have guessed that a true LP tire would be in the 65-70 Series range. Some auto tires are down to 50 Series, maybe lower from what I've seen on the road!
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« Reply #16 on: July 03, 2007, 09:24:55 PM »

As far as ride quality goes-my bus originally had 12R-22.5 with steel wheels on it.  I took my 11R-24.5's on Alcoa's to my mechanic in Washington to have switched.  The mechanic, that has worked on too many buses to count said that the 11R-24.5's were the smoothest, best riding tire he's ever felt.

As to the 12R-22.5, the only truck I've seen them on is a heavy haul, logger, fire truck, dump truck (all local type trucks), but have never seen them on an over the road truck.  The main reason that truckers are using the standard low profile 22.5 (295/75R-22.5 or 275/80R-22.5)is because of the higher trailers and having to have a lower frame height.  The standard low profile 22.5's run cooler, cost less, get better fuel mileage than the 24.5's-mainly because the tire manufacturers are not spending any time on them.  The USA and Canada are the only countries that use 24.5-22.5 is the standard world wide.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #17 on: July 03, 2007, 11:45:39 PM »

Other factors to consider:  The 22.5 wheels give a softer ride than the 24.5.  This is why many truckers use them, and it is why buses were almost exclusively fitted with this diameter wheel.  As has already been mentioned, you need to pay attention also to revs/mile, which vary among tire models even in the same size, and will vary more if you change wheels.
-Sean
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Sean I very seldom find anything in your posts that I find a need to question or that I disagree with, but this is one I must do both on! The wheels themselves don't make a differance about the ride, it's the tires! And also if you'll check specs on the Eagle buses (which a notably some of the best riding buses ever built! Especially since they didn't have fancy air ride systems!), I think you'll discover they came out almost exclusily with 24,5"s. At least all of them I've ever worked on, been around, or seen listed for sale had 24.5"s. So if 22.5"s are so much better riding tire, why do Eagles have the best ride there is? (with exclusion of there successors Setra's which were/are both products of Kassboro & Setra has that Eagle ride beat with it's independant front air ride suspension!). Also I used to be a trucker and I always either spec'd my trucks with 24.5" tall rubber, or if it came with it I took it and had it switched! And all my LARGE CARS rode like dreams! FWIW BK Grin
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« Reply #18 on: July 04, 2007, 04:54:03 AM »

A side note to Busted Knuckle's comment on "fancy air suspension"- actually the rubber torsilastic suspension that Eagle and Flex used is alot more complicated from a design point and also for working on them.  In my opinion, there is nothing more simple than an air suspension system-usually a straight axle with three or four trailing arms and one cross positioning arms, two or four air bags per axle and a leveling valve with air supply.   Just ask someone that has rebushed and rebagged an air suspension system compared to re rubbering the torsilastic and re bushing it!  Good Luck, TomC
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« Reply #19 on: July 04, 2007, 05:11:31 AM »

I tried 11R22.5's on the steer on my bus and found the smaller size tire also lowers your ground clearance which may not matter to some if you only run on the hiway and go to nice modern parks but i like to go to some more primitive parks and area's . Jerry
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« Reply #20 on: July 04, 2007, 05:15:31 AM »

For a simple system, I think my leaf springs have both your torsilastic and your airbags beat.
Sure, it may ride a little rougher, but...

10.) Rebushing is a snap.
9.) I don't have to wait for it to air up.
8.) Leaf springs don't leak.
7.) Leaf springs don't need plates welded on top of the airbeam to keep the air inside.
6.) If I break a leaf, most likely I can still go down the road to a safe place without wearing out a tire.
5.) Leaf springs don't need to be recalibrated.
4.) Leaf Springs don't rot.
3.) Leaf springs don't have complicated leveling systems.
2.) Leaf springs don't "porpoise" when traversing city streets.

And the #1 reason leafsprings are better than the others...
   The bus won't squash me when I crawl under it!

 Grin
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« Reply #21 on: July 04, 2007, 05:20:07 AM »

All valid points-but it's da ride, da ride! Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #22 on: July 04, 2007, 07:48:28 AM »

Fred, thanks for bringing this up.  Some folks have made points here that hadn't been discussed before (to my knowledge), and it's helped me. 

Since my health is now letting me get back to work on the coach, the first thing I need is six tires.  Pieces of information - it's a PD-4107, total weight under 26,000 lb so its a light bus.  We both still work, so the tread life isn't an issue - the sun will get to them before the highway does.  Currently, coach has 12Rx22.5's.  Most driving will be highway, improved surfaces - we're not planning any rock climbing or gully crossing.

So, here's my plan for tomorrow (Thursday) or Friday - unless someone here says I'm really off base.  Calls to local tire shops (Dallas, TX area) found a place with the best prices, also had been recommended by the local shop of a national bus sales/maintenance organization. 

Recommended options and prices from them are:

Firestone FS560, 12Rx22.5 - a Regional tire but with 75 MPH top speed, 487 Revs/Mile (8 RPM lower than Russ' 495 - a little better top speed but a little taller for first and reverse) - price before tax, mounting, etc. $302.

Firestone FS 590 Plus, 11Rx22.5 - a Highway tire, 503 Revs/Mile (8 RPM higher than the 495 - a little off top speed and fuel economy, but nicer on the clutch in first and reverse).  I also suspect that the fuel economy will be a wash (versus the 495, maybe not the 487) if it lets me delay downshifting on hills.  Price, before tax, etc. is $276.44, probably a savings of around $28 each with tax, or $168 total. 

As of yesterday, this major local tire supplier had 8 12R's in stock, but 56 11R's - which tells another part of the story.  Tire guy also mentioned that the 11R's will be easier to find on the road. 

So, my decision - thanks in part to all the earlier posters in this and other tire threads - is to go with the 11R Highway tires.  Price saving, availablility, are factors, but one of the deciders for me is the Highway vs. the Regional tire.  By the way, why Firestone? - best price among brands - and I've run fleets of Firestones in transit service with no noticeable difference to other brands.

Now, to be fair, this may cost me more net money if I end up with seven tires - since I probably shouldn't use one of the existing 12R's for a spare.  I'm hoping to find a used tire there that can be a spare. 

Now, that has been another discussion - but maybe someone here has a thought.  If 11R22.5's are so popular, does that suggest that I shouldn't carry a spare?  Again, a piece of information - I don't plan to change my own tires, here or on the road.  My preferred method of removing stud-piloted rear duals is to find out if either Visa or Mastercard is accepted.  Yes, I have the tools and the knowledge if it's an emergency.  My first job in the bus industry was sweeping and fueling buses, but that also ended up as somewhat of a mechanic's helper - including breaking down and building up split rim bus tires with sledgehammers and bars.  However, I'm not in my teens anymore, and I've become a little too familiar with the ins and outs of health insurance - to want to take the risk.  If I'm the only qualified driver, and hurt my back by lifting a tire, it'll cost a lot more than it would to call the road service folks.

I know this was a long post, but I wanted to explain my thought pattern - in case it helps someone else think through the options.

So, to all - thanks for the help.

Arthur
« Last Edit: July 04, 2007, 02:06:53 PM by Runcutter » Logged

Arthur Gaudet    Carrollton (Dallas area) Texas 
1968 PD-4107

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kyle4501
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« Reply #23 on: July 04, 2007, 08:43:19 AM »

. . . . . Now, that has been another discussion - but maybe someone here has a thought.  If 11R22.5's are so popular, does that suggest that I shouldn't carry a spare?  Again, a piece of information - I don't plan to change my own tires, here or on the road.  My preferred method of removing stud-piloted rear duals is to find out if either Visa or Mastercard is accepted.  Yes, I have the tools . . . . .
Arthur

The need to carry a spare depends on each individual's circumstances or comfort level.

Some of my thoughts on needing to carry a spare:
- If you intend to stay on improved roads, risk of needing a spare is low.
- Can you afford to loose a day or 2 to get a tire replaced during your travels?
- If you don't use the spare, it will age faster than one in use & you may find it unsuitable for service several years from now - time does fly when you're having fun  Grin
- Can you afford the expense of buying a tire while traveling?
- Can you afford the cost of carrying a spare - lost storage, buying a tire you may never use, etc.
- Can a single tire on the rear safely carry the weight to drive to the next open service station?

I'm sure there are more factors to consider, but you get the idea.
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« Reply #24 on: July 04, 2007, 09:02:11 AM »

I don't carry a spare, nor did I when I was truck driving (very few trucks carry spares) even though I was an irregular truck driver with being in all parts of the country-many times off truck routes.  I also have the Doran wireless tire monitor that will alarm you if the tires go down beyond a certain point.  At which time you can pull over and find out why the tire is running low.  Most times the tire will have picked up a nail or such, where you can just add air to the tire to get you to the next tire service place (You do have an air hose and hook up to use the air system of the bus for tire inflation, don't you?!).  If you have a tire failure or blow out (which is very rare if the tire pressures are up to specifications-most blow outs are caused from low tire pressure which causes a hot running tire that fails) you can just call a mobile tire man (of which are in just about every town) to bring out a new tire.  I think you're making the correct choice on going with the 11R's.  You may loose some top speed, but you'll have a little better startability, and if you're like most of us, don't go barreling down the road up against the governor, you're fuel mileage might actually be better, since you won't be working the engine quite so hard (but I bet you won't even notice).  Good Luck, TomC
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Sean
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« Reply #25 on: July 04, 2007, 10:46:44 AM »

... The wheels themselves don't make a differance about the ride, it's the tires!


Yes, absolutely... it's the tires.  But if you look at the 11R24.5 vs. the 12R2.5, you will see that for nearly the same overall diameter, you have another inch of sidewall, which gives the whole assembly more room for flex.  So, it's the tires -- but the wheel, in this case, enables the better-riding tire.  So, common wisdom in the coach industry is 22.5 gives you a better ride.  FWIW.

Quote
And also if you'll check specs on the Eagle buses (which a notably some of the best riding buses ever built! Especially since they didn't have fancy air ride systems!),...


Actually, the Torsilastic suspension is, IMO, exactly the reason Eagles had such a great ride.  Much better-riding suspension than air.  That's the reason a bunch of Eagle fans are trying to bring the brand back.

That being said, Eagles don't constitute a majority of buses made, by any stretch.  Even if we stick just to the US (as it has already been noted that 22.5 is the standard nearly everywhere else, including Europe and Central/South America), GM and MCI together account for the lion's share of the market, past and present, and 12R22.5 (and, more recently, 315/80R22.5) account for the majority of tires/wheels on those brands.

And, of course, Eagle is no longer (not counting the new start-up, which has yet to sell even a single bus), so virtually every parlor coach rolling off the line today has 22.5" wheels, either 8.25" or 9" in width.

Not disagreeing with anything you said -- just explaining why I said "almost exclusively" (and note, I did say "almost").  Smiley

-Sean
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« Reply #26 on: July 05, 2007, 12:19:24 AM »

Thank uyou for all the replies .Most informative.

Like someone else on this thread I don't put a lot of miles on my bus. I use it locally a few times a year and usually have one major trip each year. Which means that my tires don't get used much BUT still deteriorate. My reason for wanting to switch to a tire that is used extensively in the trucking industry is to buy used tires more frequently. As you can appreciate I don't reqiure a lot of tread wear. I would much rather spend $100 every few years on an "almost" worn out tire than $4 or $500 on a tire that I have to get rid of thst still has 75% of the tread left.

Thanks

Fred Mc.
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« Reply #27 on: July 05, 2007, 03:19:43 AM »

You might want to consider buying new tires and then selling them befor they start to weather. That is what I am trying to do. It recently cost me about $300 to upgrade up to 2 new tires.
                       HTH Jim
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« Reply #28 on: July 05, 2007, 07:04:57 AM »

It'd be tough for me to replace tires on my bus if they were still good - I'd put it off 'just a little bit longer' & end up with tires no one wanted  Sad

Also, on an RV, the tires are more likely to have been abused & a trucker might not want to take a chance on something that could cost more than he saved.

If you buy used off a truck, you will be getting tires a year or 2 old.
You may have sucess in finding a smaller trucking company that would like to get a little better 'trade-in' on their tires.

Sometimes you can get lucky with the local truck tire store & they will work with you & watch for a good set of takeoffs.

Good luck.
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« Reply #29 on: July 05, 2007, 07:39:54 AM »

I looked around for used tires. I'm cheap, I'm a bargin hunter and not afraid to negotiate. I tried many different places and could find nothing in used that I would spend my money on. Let alone bet my life on! I'm cheap not stupid.
 I know some people seem to have better luck or maybe its skill. But from what I could find I would rather buy new.
 These are steer tires I am referring to. Although I would not have bought anything I saw for any position on my bus!
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