Bus Conversions dot Com Bulletin Board
August 27, 2014, 02:04:59 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you had an E-Mag Subscription: It will not be stolen by your mailman or your neighbor who also may be into buses.
   Home   Help Forum Rules Search Calendar Login Register BCM Home Page Contact BCM  
Pages: 1 2 [All]   Go Down
  Print  
Author Topic: Tire size 900x20?  (Read 7600 times)
happycamperbrat
Hero Member
*****
Offline Offline

Posts: 1813





Ignore
« on: April 30, 2009, 07:32:59 PM »

I am thinking about buying a cheap bus just to get the tires. I found this ad http://cgi.ebay.com/ebaymotors/1979-Wayne-International-65-Passenger-School-Bus_W0QQitemZ330326451792QQcmdZViewItemQQptZBuses?hash=item330326451792&_trksid=p4506.c0.m245&_trkparms=65%3A1%7C39%3A1%7C240%3A1318 and the tire size is 900x20 I have never heard of such a thing...... of course I am new to all this. But I have 12x22.5 and have read that there may be another number that would be the same as my tire, like a metric number. I dont know metrics, what size of tires should I be looking for? I am confused... as usual
Logged

The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post
rgrauto
Full Member
***
Offline Offline

Posts: 116





Ignore
« Reply #1 on: April 30, 2009, 08:24:12 PM »

Hello Happycamper, The 900x20 is older technology and not knowing what kind of bus you own they may not fit you bus.  You say you have 1200x22.5 tires.  It would be less expensive to use a 1100x22.5 tire.  Most all trucking companies use 1100x22.5 tires, so if you shop around you might buy some good take off tires or retreads for rear without spending a lot of money because they are the most common tire. Hope this helps.
                                             Glen
Logged
belfert
Hero Member
*****
Offline Offline

Posts: 5420




Ignore
« Reply #2 on: April 30, 2009, 08:30:14 PM »

$700 for a bus with "usable condition" tires of a strange size is probably not a bargain.

Bus fleets tend to put the worst tires they have on a bus that is being sold.  "Usable condition" could mean barely legal, but not quite bald.
Logged

Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
gus
Hero Member
*****
Offline Offline

Posts: 3504





Ignore
« Reply #3 on: April 30, 2009, 08:49:47 PM »

These are tube type tires and are probably mounted on two piece wheels, you don't want to mess with these.

It is basically the same size tire as 900 x 22.5 which is tubeless. This size is too small for the great majority of our buses.

Wheels can be changed from one vehicle to another if the lug pattern is correct but the tires can't be changed between the wheels.
Logged

PD4107-152
PD4104-1274
Ash Flat, AR
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2548


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #4 on: May 01, 2009, 01:03:11 AM »

... But I have 12x22.5 and have read that there may be another number that would be the same as my tire, like a metric number. ...


You most likely have 22.5" diameter, 8.25" wide tubeless rims on 15 drop centers.  This is a standard and very common wheel size.

The 12R22.5 tires fitted to your bus are rated at a certain load.  While it is true that 11R22.5 tires will also fit those rims, as suggested by others, there are three potential problems with this:
  • 11R22.5 tires have a much lower load capacity than 12R22.5 tires.  Before you can change to this size, you will need to actually weigh each wheel position and ensure that the smaller tire can safely carry your load.
  • This tire is actually a smaller diameter.  That means that your speedometer will be incorrect (reading too high) unless you recalibrate it, and your top speed will also be lower.
  • The smaller diameter can also impact ground clearance, which may or may not be a problem for your coach.

There is a metric "substitute" for the 11R22.5 size, which has all those same limitations.  That size is 265/75R22.5.

There is also a "metric" tire that can substitute for the 12R22.5, which is the 315/80R22.5.  This is, however, a much beefier tire, intended for heavier loads than the 12R22.5 can handle.  It is much harder to find, much more expensive, and has higher Federal Excise Tax (FET) than the 12R22.5.  Unless you have a real need for the load capacity, I would stay away from this size.

Bottom line, 12R22.5 is a very common size, and absent really good reasons to change, you are probably better off sticking with it.  If you are trying to save money on tires, get a quality set of new steer tires from one of the less expensive brands, such as Firestone, and then ask around at your local truck tire dealers about take-offs for the other positions.  Many dealers will have used take-offs with plenty of legal tread left for about $100 or so in that size, and there is no FET on used tires.

Lots of information on this topic in the archives as well.

-Sean
http://OurOdyssey.BlogSpot.com
« Last Edit: May 01, 2009, 09:02:17 AM by Sean » Logged

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

« Reply #5 on: May 01, 2009, 01:59:08 AM »

Sean,

I think you'll find that the 11R22.5 size interchange is closer to 285/80R22.5 and the 12R22.5 is closer to the 305/80R22.5
315/80R22.5 which is standard on many buses is actually closer to 12.5R22.5
265/75R22.5 is a low profile tire equal to a 10.50R22.5

http://www.csgnetwork.com/tireinfo4calc.html
Logged
Singing Land Cruiser
Michael & Christi Hargis
Hero Member
*****
Offline Offline

Posts: 738


Looking for another Bus


WWW

Ignore
« Reply #6 on: May 01, 2009, 06:17:47 AM »

I had a 1967 M35A2 Deuce & 1/2 that had that size tire on it. 10 new street tread cost $1,200 in 2007. I uesd it for parades. M&C
Logged

Entertainers/BUSNUTS
http://singinglandcruiser.blogspot.com/
Master Mason, Noble Shriner
Where "R" We ; Leeds, Utah
TomC
Hero Member
*****
Offline Offline

Posts: 6733





Ignore
« Reply #7 on: May 01, 2009, 07:49:18 AM »

Any truck/bus tire with a whole number diameter-like 20" or 22" is a tubless tire.  900x20" translates to a 9" x 20"-much smaller then your 12"x22.5.  Rim diameter dimensions with .5 in them are tubless-like 19.5, 22.5, 24.5.  Don't buy a bus for their questionable tires.
Just a general comment-I get a bit miffed with the lax attitude that some have on the board about tires on the bus.  Tires are much more then big round rubber things that hold air.  Tires are the only contact you have with the road, the only means by which to control your bus, and to stop it safely.  Michelin makes 45 different truck/bus model tires alone just for on and on/off highway use. Please do yourself a big favor and not be cheap about your tires-be cheap elsewhere.  Buses are among the heaviest vehicles on the highway (actually are heavier then big rig trucks when you factor in that we are loaded all the time with less axles), put the biggest strain on tires-especially when maneuvering.  Buy new tires that will give you many years of faithful, worry free service.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Don Fairchild
Hero Member
*****
Offline Offline

Posts: 753




Ignore
« Reply #8 on: May 01, 2009, 08:48:53 AM »

Hey girl;

It was nice to have you come by the shop the other day. How did the ordeal come out with the rear brake.
I belive the tires On your RTS  were 1200:22.5's Stay with them. You can look around at the tire shops and maybe find some good used tires that will get you by for a short time while you are getting used to driving the bigger bus.. If not save for new one and do it right the first time. takes a load off of the mind while on the road.


Hope this helps.  come by and say hi next your in town.

Don
Logged
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2548


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #9 on: May 01, 2009, 08:54:23 AM »

...
I think you'll find that the 11R22.5 size interchange is closer to 285/80R22.5 and the 12R22.5 is closer to the 305/80R22.5
315/80R22.5 which is standard on many buses is actually closer to 12.5R22.5


All true, Dallas, except that 285/80R22.5, 305/80R22.5, and 12.5R22.5 are not sizes that exist in the real world.  I know you can special-order some of these sizes in certain places, but you would then likely be waiting weeks or months for the small-batch production run needed to make them.

Bridgestone, for example, which is one of the largest suppliers of heavy tires in the US, does not list any of those sizes in its catalog.

I was trying, in my discussion, to stick to items one might actually find at a tire dealer (or on an existing vehicle).  FWIW.

I probably should also have mentioned the 295/80R22.5 as a possible substitute for the 11R22.5, although that tire is typically fitted to 9" rims rather than 8.25".

-Sean
http://OurOdyssey.BlogSpot.com
« Last Edit: May 01, 2009, 09:01:38 AM by Sean » Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
TomC
Hero Member
*****
Offline Offline

Posts: 6733





Ignore
« Reply #10 on: May 01, 2009, 09:57:39 AM »

I guess some are making up tire sizes.  Looking in my Michelin book, I see a 275/80R-22.5 and the other manufacturers make the 295/75R-22.5-but no 285/80R-22.5-there is a 295/80R-22.5 though.  In regional transit bus tires, there is a 305/70R-22.5, a 305/85R-22.5, but no 305/80R-22.5.  Also, 315 converts almost exactly to 12.007874, not 12.5 (which doesn't exist).  If you have 12R-22.5's, they are the older bus tires that will be cheaper then the newer 315/80R-22.5.  Use the 315's if you have a weight problem.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
busshawg
Sr. Member
****
Offline Offline

Posts: 490





Ignore
« Reply #11 on: May 01, 2009, 11:30:26 AM »

 As mentioned these tires are old technologie and I would be careful about buying old tires. If he tires are new that's fine but not aways is a good looking tire a good tire, meaning if they are old you might find yourself going to all the work of getting these tires and switching them and get down th eroad far enought to get them warmed up and boom, there's the first one gone. I personally would never go back to 900 x 20 tire.

Have Fun
Logged

Have Fun!!
Grant
Dallas
Guest

« Reply #12 on: May 01, 2009, 11:45:29 AM »

Sorry if I upset your sensibilities Tom.
When I went to school 305 mm was 12.007874015748031" Maybe California changed it and didn't tell the rest of the world?
315 mm was 12.401574803149606"
265 mm was 10.433070866141732"
275 mm was 10.826771653543307"
285 mm was 11.220472440944881"
295 mm was 11.614173228346457"

I was speaking to Sean in generalities, not in specifics, especially not in the specifics of only using one catalog to quote from.
I'm glad you live at such a lofty altitude.

I guess some are making up tire sizes.  Looking in my Michelin book, I see a 275/80R-22.5 and the other manufacturers make the 295/75R-22.5-but no 285/80R-22.5-there is a 295/80R-22.5 though.  In regional transit bus tires, there is a 305/70R-22.5, a 305/85R-22.5, but no 305/80R-22.5.  Also, 315 converts almost exactly to 12.007874, not 12.5 (which doesn't exist).  If you have 12R-22.5's, they are the older bus tires that will be cheaper then the newer 315/80R-22.5.  Use the 315's if you have a weight problem.  Good Luck, TomC
Logged
TomC
Hero Member
*****
Offline Offline

Posts: 6733





Ignore
« Reply #13 on: May 01, 2009, 12:41:37 PM »

Sorry all-Dallas is correct-I was using the wrong multiplyer.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
gus
Hero Member
*****
Offline Offline

Posts: 3504





Ignore
« Reply #14 on: May 01, 2009, 08:14:44 PM »

TomC,

I have to disagree with you, 9.00 x 20 is not a tubeless tire. Only the .5 sizes are tubeless.

Liken SLC, I had a M35A2 Deuce & 1/2 that had 10 of that size tire on it, all had tubes.  I also have a '42 GMC ten wheeler with ten 7.50 x 20, all with tubes, a '52 GMC with 12.00 x 20, all tubes and a few others with 9.00, 10.00 and 11.00 x 20, all with tubes.
Logged

PD4107-152
PD4104-1274
Ash Flat, AR
TomC
Hero Member
*****
Offline Offline

Posts: 6733





Ignore
« Reply #15 on: May 01, 2009, 09:45:16 PM »

Gus-you are correct-I wrote it wrong.  Even wheel diameters are TUBE type tires-like 20" and 22".  TUBELESS is with a .5 at the end.  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2548


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #16 on: May 01, 2009, 10:28:55 PM »

I guess some are making up tire sizes.  ...

Tom, I think it is simply a case of the Javascript size calculator, for which Dallas posted a link, not actually being in any way cognizant of what sizes are actually manufactured.  It's just a straight across calculator, converting inches to the nearest 5mm increment and vice versa.  I believe it translates the aspect ratio for any pre-metric size to 80%.

-Sean
http://OurOdyssey.BlogSpot.com
Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
Jerry32
Hero Member
*****
Offline Offline

Posts: 726





Ignore
« Reply #17 on: May 02, 2009, 12:21:48 PM »

I put larger wheels on mine and used 11R24.5's which keep the hieght up for clearance as the 11R22.5"s are smaller around. Jerry
Logged

1988 MCI 102A3 8V92TA 740
Busnut83
Full Member
***
Offline Offline

Posts: 179




Ignore
« Reply #18 on: May 02, 2009, 04:29:20 PM »

My question is can I switch my front 12r22.5 tires and wheel with a 11r24.5 on my 83njt mci-9 ?
Logged
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2548


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #19 on: May 02, 2009, 11:06:52 PM »

I put larger wheels on mine and used 11R24.5's which keep the hieght up for clearance as the 11R22.5"s are smaller around.


and

My question is can I switch my front 12r22.5 tires and wheel with a 11r24.5 on my 83njt mci-9 ?


I hear this all the time:  11r24.5 are cheaper and easier to find than 12r22.5.  Both true, however, I have studied the cost difference and the availability issue, and, frankly, most of us will not save enough over the lifetime of our buses to justify the expense of changing the wheels.

The short answer is, yes, you can change wheels.  Make sure you get the correct mounting (hub-pilot versus stud-pilot aka "Budd"), correct hub bore, and correct bolt holes for your application.  Then, make sure you recalibrate your speedometer, and, if DDEC-equipped, the DDEC RPM parameter.  Lastly, measure your wheel-by-wheel weights to get the correct load range and inflation for the new tires.

Remember that the 24.5 wheels will give a stiffer ride than the 22.5 wheels under all conditions.

-Sean
http://OurOdyssey.BlogSpot.com
« Last Edit: May 02, 2009, 11:12:45 PM by Sean » Logged

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

Posts: 2548


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #20 on: May 02, 2009, 11:08:48 PM »

(deleted - posted in error)
« Last Edit: May 02, 2009, 11:12:12 PM by Sean » Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
TomC
Hero Member
*****
Offline Offline

Posts: 6733





Ignore
« Reply #21 on: May 02, 2009, 11:11:59 PM »

Sean- I'm not quite sure how a 24.5 can ride stiffer then a 22.5.  Both a 11R-22.5 and 11R-24.5 have the same aspect ratio making the side wall height the same on both tires-sidewall height is where you get the tire ride.  I have 24.5's on my bus, and when I first put them on, my mechanic said he had never felt such a smooth ride compared to 12R-22.5's.  So how do you explain that? (no insult intended!).  Good Luck, TomC
Logged

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Sean
Geek.
Hero Member
*****
Offline Offline

Posts: 2548


'85 Neoplan Spaceliner "Odyssey"


WWW

Ignore
« Reply #22 on: May 02, 2009, 11:14:54 PM »

Sean- I'm not quite sure how a 24.5 can ride stiffer then a 22.5.  Both a 11R-22.5 and 11R-24.5 have the same aspect ratio


Tom,

Sorry, I was perhaps not clear.  I said that the 11R24.5 would be a stiffer ride than a 12R22.5.  You can't really compare 11R24.5 to 11R22.5 -- they have vastly different diameters and load ratings.

-Sean
http://OurOdyssey.BlogSpot.com
Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
Our blog: http://OurOdyssey.BlogSpot.com
RJ
Former Giant Greenbrier Owner
Hero Member
*****
Offline Offline

Posts: 2795





Ignore
« Reply #23 on: May 03, 2009, 02:36:35 PM »

Happy Camper -

Don mentioned that you have an RTS.  The original factory tires on your coach were 12R22.5s.  This tire size was chosen for a vehicle in revenue service.

For RV use, many busnuts have gone to the smaller 11R22.5 size, for various reasons - mostly because the 11s are less expensive than the 12s. 

Generally speaking, unless your interior is outfitted with marble floors and granite counter tops (i.e. HEAVY), this isn't a problem.

As Sean said, however, it does mess with your speedometer readings, fuel mileage and ground clearance.  These may, or may not, be a concern to you.

The bus/trucking industry is slowly converting to metric sizing, just like automobiles use.  It will be awhile, so a lot of the old numbers are still current and useful, but that's changing.

Most newer coaches are coming with 315/80R22.5 tires, which, as has already been mentioned, is approximately the same size as your 12R22.5s.  Not enough difference to really quibble over.

HOWEVER -

Be aware that bus tires are made in a couple of different configurations - one for regional or city use, and one for long-haul or highway.  The difference is in the sidewalls primarily - those designed for city/regional use generally have heavier sidewalls, because transit bus operators thoroughly believe that curbs are part of the braking system when pulling into a bus stop. 

City/regional tires also have a lower speed rating than highway tires, usually 50 mph vs 70-75 mph.

So be careful when shopping for tires - do your homework!!

FWIW & HTH. . .

 Wink
Logged

RJ Long
PD4106-2784 No More
Fresno CA
happycamperbrat
Hero Member
*****
Offline Offline

Posts: 1813





Ignore
« Reply #24 on: May 03, 2009, 08:45:01 PM »

Wow! I am impressed with all this info! You guys have all given me loads to think about with the tire issue. And a special hello to you Don and thank you for letting me and my mother see your beautiful coach (she still is talking about your mirrored ceiling)!

It seems tires are the single biggest expense with a bus over the lifetime of it. My tires LOOK like brand new, but they are 8 years old and that scares me from what I have read. I would definitely buy brand new for my steers but I am looking for a cheaper way for my back tires on my RTS.

Thank you,
Teresa
Logged

The Little GTO is a 102" wide and 40' long 1983 GMC RTS II and my name is Teresa in case I forgot to sign my post
Pages: 1 2 [All]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.18 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!