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Author Topic: 12R 22.5 or 11R 24.5  (Read 10960 times)
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« on: March 17, 2007, 03:14:05 PM »

 I'm sitting on the fence on this. I've researched the archives. Cant see any reason I should put the same tire on my MCI5C that people are putting on 40,50,60 thousand pound buses. That are 40/45 feet long.
 The first response I come up with is to go by da book. Use what was spec'ed for the bus. Well da book says 11.50X20 or 12.50X22.5 are they even available anymore?
 I've visited several tire sites and the 11R 24.5 14 or 16 ply tires are rated for more weight than the front of my bus.  11,060 lbs front axle, bus fully loaded. rear is 18,620 total is 29,680.
 The minimum 14 ply I find is rated at 6045 lbs single. and 16 plys are rated at min 6610 lbs If I buy the lowest rated tire I would have a total of 12,090 pounds. That is 1030 pounds over my front axle wieght. and that is the worst I can do.
 My current tires, Michlen XZE 12R 22.5 are 486 rpm the 24.5 are 480. I know this will change my speedometer reading, but I have a new one sitting in a box, it has the dip switches.
 Am I missing anything here? Replys, opinions are always appreciated.
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« Reply #1 on: March 17, 2007, 03:39:41 PM »

OMG the can of worms you opened!

I vot 12r22.5........it is after all a bus tire.

they ride better than an 11x24.5
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« Reply #2 on: March 17, 2007, 04:12:09 PM »

JJR, I'm in the same boat (so to speak) for my 4107.  You might check out the discussion of "Wheel Width" now on page 2, as some of the folks responded to my fence sitting - and my asking about another option, 11R 22.5's.

Arthur
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« Reply #3 on: March 17, 2007, 04:29:53 PM »

JJ, I don't have a real background into why busses used 1200 rubber and 16 plys. I know the 1200 puts an extra inch between the wheel and the ground and that is why 1200/22.5 and 11/24.5 turn aprox. the same revs per mile. We pay Fed Excise tax on tires by the lb. That adds to the cost, 1200s weigh more and are also becoming rare. I suppose 1200 may give a slightly better ride, but thats a guess. I have not blown a steer tire on a bus but have blown one in a truck. When that 1100 blew (it seems like yesterday but wasn't) I thought that the wheel had left the truck, because it dropped so far to the wheel edge (maybe 11 inches)? Thats the scary part, and when you as a driver have to make good decisions. The first instict is to grab a lot of brake, but really you want to grab some throttle and let it settle down and then use a little brake to stop ,so you don't turn it sideways. I have circle track experience and have blown many steer tires on the track and always thought I was prepared for a truck tire blowout on the steer axle. I'm sure the experience helped me, but the racecar tire would drop about 4 inches and the truck tire dropped almost a foot. To give you an idea what you are going to be dealing with if you blow a steer on the bus, remove the right front tire and wheel, demount the tire and replace the wheel without the tire on the bus and take the jack out. INTERESTING HUH. Thats what you could be driving at freeway speeds! Does the wheel even lift the bus high enough to keep the right front corner from dragging the ground? If you have 1200 tires, it is going to drop 1 more inch farther, 12 inches, and the inch factor and the pucker factor are related in my opinion. So if you replaced the 1200/22.5 with 1100/24.5 you would gain 1 inch of steel wheel between the front corner of your coach and the ground if you blew that tire, and reduce possible damage as well as a few heart beats less sheer terror, since it would not drop as far. I have practiced the blown steer tire senario with my wife when she is driving. I yell BOOM in her ear, (she loves me) and she now knows to lock both hands on the steering wheel, straight ahead and to keep the throttle on until things settle, then ease off the road without heavy braking.
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« Reply #4 on: March 17, 2007, 06:32:26 PM »

Jim, I am going to 24.5 to help my rpms.  And also easier to find, but just an idea. Is your bus a Saudia bus? My 5 came from Az an they said they sold others, so I wonder if I will find some one who has one.  Thanks  Tom Y 
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« Reply #5 on: March 17, 2007, 06:53:16 PM »

Yup, its a Saudi! Rumored to be Osama's personal ride.  In the water fill door there is a sticker in Arabic! I bought the bus in Washington state.
 The taller tire for higher speed does not make sense when looking at tire websites. A 12r 22.5 has an rpm of (depending on manufacturer) 480rpm an 11R 24.5 has an rpm of 483. Unless you are looking at 12R 22.5 vs 12R 24.5, I did not research that.
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« Reply #6 on: March 17, 2007, 07:10:55 PM »

When I bought my coach it had 11R x24.5 on the rear and 12R 22.5 on the front, I made the change so I would have all the same tire all around and  went with the 11R x 24.5  16ply.  This is on a mc8.
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« Reply #7 on: March 17, 2007, 07:36:57 PM »

I've had 12R 22.5" and now have 11R 24.5" and I can't tell any difference in the ride. I did have all my tires balanced.
  I changed for the availability of Alcoa's in 24.5 are much easier to find(and cheaper) than in 22.5"
I paid $100 each for freshly polished (used) Alcoas. (and I was able to inspect each wheel b4 I paid)
   I also paid $100 each for Goodyear takeoffs.
 I would just as soon have the 22.5" if they were the same deal-HTH Chuck
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« Reply #8 on: March 17, 2007, 11:49:46 PM »

NJT5573 stated that with a 12" tire you have 12" to go to the rim.  That isn't quite true.  All tires have an aspect ratio- like a 65 series or a 75 series, etc.  That is the percentage of height to the overall width of the tire (listed tire width is the overall width of the tire carcass, not the tread).  So for instance, on a 11R-24.5 by NJT's theory, that sidewall should be 11" tall.  Multiply that by two side walls (top and bottom of the tire), and you get 22".  Add 24.5" of rim and you should have a 46.5" diameter tire.  Not true!  The tires on my bus are Michelin 11R-24.5 16 ply that are 43.5" in diameter, not 46.5".  So my tire has an aspect ratio of 86.3%.  To figure diameter of a tire, take the width-11" multiply by the aspect ratio, which in this case is .863 you get 9.493.  Multiply that by two for the top and bottom of the tire and you get 18.986.  Add the 24.5" rim onto that and you get a tire that is 43.486" in diameter, or very close to the advertised 43.5".  What's more interesting is that the loaded radius (measured from the ground to the middle of the axle) is 20.3", because of compression from the weight of the vehicle.  The 11R-24.5 16ply makes 478 revs per mile, the 12R-22.5 makes 487 revs per mile (according to Michelin).  After being on the road for 21 years, I can tell you that the 12R is much harder to find than the 11R-24.5 on the road.  My tires ride very well, so much so that the first mechanic that worked on it really noticed a difference when the 12R's were taken off and he took it for a drive with the 11R's on.  The most important factor to a good riding tire is the proper tire inflation (my soap box).  Always go with the best tire (translated Michelin).  Good Luck, TomC
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« Reply #9 on: March 18, 2007, 11:44:17 AM »

Tom, thanks for cleaning that up for me. I knew I was off a little and used the ? to show that. This all seems academic to me in a way since as far as I have been down the bus road is with my 77 and 89 Eagles. They both had factory 11R24.5 rubber when I purchased them. I am thankful for that because its a common size in todays world. There are many good brands to choose from with nationwide availability. I have a war memorial in my neighborhood dedicated to the 15 soldiers that died in WW1 from my County in Washington State. These men were between 17 and 23 years old and all died in France. My father also fought to protect France in WW2.(Normandy Beach). I can't tell you one thing France has done for my country. I never pass up an opportunity to piss on a Michelin so keep the tire shine handy!
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« Reply #10 on: March 18, 2007, 12:05:59 PM »

NJT, how do you know if the buses had factory 11-24.5's?

Although it is possible they were ordered this way.....or more than likely they were put on at delivery as tires were optional equipment........I doubt the 77 has 11's

a  final delivery record would be the only way to determine this.
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« Reply #11 on: March 18, 2007, 12:06:50 PM »

I've been having the same quandry.  Back a few years ago I found a football sized sidewall bubble one of my 12R22.5 Michelins on the rear.
So I pulled into the local Rip (off) Griffin truckstop and all they had in stock was some 11R22.5 steer tires, Michelin  XZA3's.
  After considerable thinking, and considering that All 6 tires were the same, I finally had them take my two front tires off and stick them on the rear, and then install the new 11R22.5's on the front.  This meant that the bus is now an inch lower in the front, but it also meant I could get back on the road instead of waiting days to get the proper tires in, and I was on a tight schedule.

The most amazing thing was how QUIET the bus suddenly was!!  My wife and I noticed immediately and were VERY impressed.

Here it is a few years later now, I've just stuck the Telma and new axle into the rear of the bus, and had the tired old springs re-arcd.  Now the bus looks like some kind of a low rider being that the front springs are still tired and the tires are too small.  It's ars is way up in the air and the front is sniffing the ground!!  I  So I figured I could put the two 11R22.5's  onto my bluebird which has 11R22.5's all the way around  anyway (and kinda needs a couple new ones on the front) and get some 12R's up there on the Crown, but I find that the only one Michelin makes in the XZA3 series is an 11R24.5.  Being that they are SOOOOO quiet, I really wanted to get XZA3's...

So considering this thread, it looks as if my question is answered, the 11R24's are the way to go!!

Thanks guys!!
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« Reply #12 on: March 18, 2007, 05:29:29 PM »

Thanks all for the info, I am set to go to a distributor for new steers this week and I have been cruising the info on tires.
I have a 5C Saudi with 24.5 Alcoa's. Think I will stick with the 11R for all said reasons.
BTW, In addition to the Arabic sticker on the Radiator fill door, mine has the "shadow" of the orig. Arabic GreyHound sticker in the SS just in front of the curb side rear tire well. You can see the slightest contrast revealing this. A friend who's native language is Arabic, translated. This Saudi came from St. Louis area. I was told that many came thru Nimco at the port of entry. Not sure how they were redeployed thru out the US.
Gary
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« Reply #13 on: March 18, 2007, 05:36:06 PM »

10 of them are in a junk yard outside Buffalo NY. Which tires are you looking at for what price?
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« Reply #14 on: March 18, 2007, 06:46:38 PM »

i have never had a problem finding 12R/22.5 any place in the west all the log trucks run the 12R /22.5  on the front that i saw at southern oregon diesel i replace my tires every 4 years now and haven't had to shop for tires.we have a great dealer in les schwab tire  no hidden fees and credit for your old tires
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« Reply #15 on: March 18, 2007, 08:00:18 PM »

Largest diameter (cover bump & pot holes), lightest tire (least number of ply), lowest or minimum tire's psi as per vehicle axle's load weight according to tire manufacture's weight spec.to achieve softer flex, softer rubber compound tread to achieve softer flex but wear faster, tire availability & cost are the what you want to consider for softer ride.
However the two biggest factor are the largest tire dia & lowest psi give you the best buy for your money to achieve your goal. So look for most available large bus or truck tire with rib treads such as Michelin XZA2.....large rib groove allow more water to enter while rubber tread achieve maximum contact pressure to surface. I believe Michelin XZA2 has the softest tread's durometer than any other brand but still last long enough.

FWIW

Sojourn for Christ, Jerry
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« Reply #16 on: March 18, 2007, 10:15:42 PM »

Tekebird, I think the 89 Model 20 was factory 11R24.5 because it was part of NJTs fleet and I've seen alot of her sister coaches. All were equiped with 11R24.5 Alcoas. I may have wrongly assumed the 77 or 79 (can't remember for sure and don't want to go dig the title out this late) was factory 11R24.5. I know it was a Continental Trailways for 10 years. It was then refurbished with 10 caps and sold to a college in Brevard County Florida that traded it to Bart Grabhorn for a newer coach after about 8 years of running the sports teams around. I purchased it in 1995. Its serial number is 19797. Its probably to new for split rims and 20 inch wheels but may fit into the 12R 22.5 era. It came to me with the 24.5 and I don't think Bart changed the wheels. That leaves Trailways and the refurb outfit as possibilities. If you have access to the history on this coach, let me know what you find.
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$1B in $1000 bills = 800 feet high.
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« Reply #17 on: March 19, 2007, 01:16:18 AM »

I have not had a problem finding the 12R either. I cannot find a 12r tire for less than $400 and that is off brands. I was quoted $532 mounted and balanced for one Goodyear! This is with the luxury of time to shop around. What will I pay if I have to buy a tire on the road ?
 Also these tires are not going to get much milage on them. I just sold 2 Michlens that were 7 years old becuse they are starting to weather check.
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« Reply #18 on: March 19, 2007, 06:50:52 AM »

jr if tires prices have went up that much i will be running these toyos for 6 years now,i will get a price today with no trade and post it for you  les schawb sells toyo,bridgestone and michelin
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« Reply #19 on: March 19, 2007, 06:57:36 AM »

I also have never had any issues finding 12r22.5..........Sometimes it isn't in stock but is brought in the next day.......plus I carry a spare so I am never left to the mercey of a road service tire sale.
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« Reply #20 on: March 19, 2007, 07:42:23 AM »

Doug -

I have several sales brochures for Eagles in my literature collection, both new and used, models 5, 10 & 20.

All of them indicate 11R-24.5 as the OEM tire size.

FWIW. . .

 Wink
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« Reply #21 on: March 19, 2007, 09:00:21 AM »

 If memory serves me right (it never does) I bougth the 2 michlens at Les Schwab in Salem Or. in 2000 I know I paid $802 for two mounted and balanced. Then it cost me another $200 to replace the studs they ruined putting them on!!
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« Reply #22 on: March 19, 2007, 10:25:51 AM »

WOW RJ, Thanks for the confirmation.......WHODA THUNK........goofy Eagles ( or should that be well before thier time)........LOL...they always were a truckers favorite bus (Only bus that looks right with aftermarket external sun visor)
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« Reply #23 on: March 23, 2007, 10:16:47 AM »

Jerry, I'm going to need 24.5 wheels if I do this, any suggestions?  Plants are doing well!
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« Reply #24 on: March 23, 2007, 07:36:52 PM »

Hi;
   After reading all the replys,  I have one more thing to add.  The 12rx22.5
   tire has a higher weight rating.  (because it is a bus tire)  That means
   additional safety overall.  Since I had a blowout on the front tire, I
   kicked it up a knoch.  I replaced the fronts with 315/80x22.5.  They
   have even a higher weight rateing.  I believe in overkill when it comes
   to tires.
                             Good luck,    Merle.
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« Reply #25 on: March 24, 2007, 02:01:45 PM »

 The nice thing about busing is  doing it your way. If the 315 tires make you happy. Go for it!!!!!  The 11R weight rateing far exceeds the weight of my bus. The only downside I see to bigger tires, is fuel mileage will suffer (not an issue with some of you rich guys) and if the power steering goes out. It may be hard to wrestle it to the side of the road.  Only my opinion of course.
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« Reply #26 on: March 24, 2007, 10:32:41 PM »

Believe it or not, the 315/80R-22.5 is the most popular tire in Europe for their big rigs.  It is the tire that is replacing the 12R-22.5.  In high speed use, you can get the tire up to 18,000lb for steering and up to 20,000lb with a 55mph limit.  Personally, my 11R-24.5 16 ply tires are a big overkill on my bus.  The steers can take up to just over 14,000lb.  Considering I have 10,500lb on the front, the 11R 16 ply is a big overkill.  I run 90psi in all my tires.  Good Luck, TomC
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« Reply #27 on: March 25, 2007, 06:53:10 AM »

Does anyone have any thoughts why bus companies run 22.5's in either 12 or the 315 metric version?

and why are the tire companies making them if only buses use them.

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« Reply #28 on: March 25, 2007, 09:37:30 AM »

Tekebird- 24.5 tires are only used in North America.  The rest of the world uses 22.5's.  The 12R's are the original tire that buses were made with in the 50's and 60's.  Now with the advent of advances in tire technology, the metric 315 (which is a 12.2" wide tire) is the replacement.  Very popular with trash trucks, dump trucks and buses.  Some of the bigger buses now are going with 365/65R-22.5 for the front and tags, with 315's on the duallers.  Good Luck, TomC
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« Reply #29 on: March 25, 2007, 09:57:36 AM »

I understand that the 315 is the metric replacement however MCI is still deliving 12r22.5's on buses.

I was just curious whhy people thought that was.......since everyone is always saying you can't find them on the road.

I have never not been able to find them, and have even looked when not in need.

Logic would have it that is the 24.5 was the "common Tire" that buses would have them....as when a bus needs a tire on the road you have 50 or so upset people.
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« Reply #30 on: March 30, 2007, 07:51:11 PM »

Here's what the tag says Huh
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« Reply #31 on: March 30, 2007, 08:29:45 PM »

 Eagle always used 11R24.5 because of its superior suspension. The others all needed help so they used a taller sidewall. The 11R24.5/11R22.5 tire width is the same on like tire models. This is an ideal footprint for a bus. Wider is not a good thing. Dump trucks, garbage trucks, fire trucks etc. are very difficult to drive in rain and snow. To much tire just skids. I bet you can't find a dump truck driver that won't laugh at you if you put "wide" tires on your coach.
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« Reply #32 on: March 30, 2007, 10:34:46 PM »


The 12R's are the original tire that buses were made with in the 50's and 60's. 


TomC -

Minor correction here, Tom.  The 4104s and 4106s, built from 1953 > 1965, all came with 11.00x20 bias ply tube tires, not 12s.  The 12R22.5s didn't start showing up until the late '60's, early '70's, starting with the 4903 Buffalo and the MC-7.  Even the mighty Scenicruiser came with 11.00x20 tires.

According to a friend of mine who's in the commercial tire industry, it won't be much longer until ALL the tires will be metric-sized.  (Just like auto tires - remember the "F78-14"?)  He also says that the 22.5s are by far and away the most popular rim size today, as more and more truckers are going to the smaller/lighter 22.5 and making up the difference in fuel mileage loss by using overdrive transmissions.  The smaller/lighter tire allows heavier loads which equals more $$ for them, as you're well aware, since you sell the things.


Ednj -

Good point, posting the data plate for your MCI.  Everyone can see specifically what MCI intended for the coach, the weight ratings per axle, and the recommended air pressure.

So, when it comes time to shop for tires, if the only thing available is metric sizing, all you have to do is sit down with your dealer and find a tire that matches the old sizing, load rating, etc.  Definitely NOT brain surgery, and most commercial tire dealers will be more than happy to work with you.


Doug -

I suspect MCI is still delivering 12Rs simply because that's what the customers are ordering.  Remember, most coaches leave the plant with tires supplied by the buyer, often thru a leasing program.


All -

Whatever tire size you finally choose, pay attention to the speed rating of the tire.  For example, on one of the major brand's sites, there are two 315/80R22.5 listed - one has a 55 mph maximum speed rating, the other has a 75 mph rating.  The lower speed-rated tire is for TRANSIT BUS operations on city streets.  These tires are built differently to withstand the constant abuse they're given in this application.  (Transit drivers think that curbs are part of the braking system, especially on the front.)  Running a transit tire at freeway speeds for hours on end, especially in the summertime, is a recipe for potential disaster. 

Do your homework, and choose wisely!!

FWIW & HTH. . .

Wink

 
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« Reply #33 on: March 31, 2007, 04:40:55 AM »

I suspect MCI is still delivering 12Rs simply because that's what the customers are ordering.  Remember, most coaches leave the plant with tires supplied by the buyer, often thru a leasing program.
 

A friend just bought a new 45' MCI shell from MCI. It came with 22.5 wheels  Jack
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« Reply #34 on: March 31, 2007, 05:11:52 AM »

Eagle superior Suspension?Huh?

Although I will give you the Eagle does have a nice Ride......as did the Flxibles with Torsilastic Suspensions, if it was truely superior in all aspects why did it not cross over into other brands?

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« Reply #35 on: March 31, 2007, 06:09:55 AM »

Jack, those tires were 315  22.5. The gross front axle weigth on that bus was a whopping 16,000 pounds!!
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« Reply #36 on: March 31, 2007, 08:43:28 AM »

Just to give you a small idea of the difference between 22.5's and 24.5's, some of the sizes 22.5's come in are: 8, 9, 10, 11, 12 (inches), 235, 245, 255, 265, 275, 295, 305, 315, 365, 425, 445, 445 (metric) with 50, 55, 65, 70, 75, 85 aspect ratios mixed in.  24.5's come in 11, 12, 275, 285, that I know of-big difference.  The 11x20 is the tube tire equivalent to 12R22.5.  19.5's are getting to be more popular with the low profile set (car haulers) and the light weight groups (liquid and bulk haulers) since they are even lighter than the 22.5's and can carry the weights.  Michelin will be bringing out a 19.5 equivalent to the big X-one 22.5's to be sized the same as the 255/70R-22.5 for use on low profile trailers and car haulers.  Michelin is the creator of most all tire advances.  Then the other tire companies lay back and watch to see if it works then bring out their versions of the tire a couple of years later.  Just like what happened with the X-one super single.  Bridgestone and I believe Yokohama both have these tires now.
 
One comment (actually I've said it before, but can't say it enough)-tires are more than big black round things that support the load.  If you go to the Michelin or any other tire manufacturer that carries commercial tires, you'll see the numerous models of tires that are very specific in the job they are supposed to perform.  I hope all of you put the tires performance and load capability above the price of the tire.  Always-safety first-if you can't afford the best of tires, maybe a little less expensive hobby would be a good choice.  Good Luck, TomC
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« Reply #37 on: March 31, 2007, 01:31:24 PM »

On a lighter bus there is no point in getting heavy duty tires, waste of money and ride quality.

Metric sizing makes no difference, the tire doesn't know or care what is written on the sidewall.
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