Tire Sizes

[Fred Mc]

Im looking to put new tires on the duals and currently have 12R 22.5 on the back and 11R 22.5 steers. As Im looking for good take-offs what other sizes can I use. I have been offered  295/75r22.5. Will these be OK. What is the equivalent to 11R or 12Rs in the metric terminlogy.

Thanks

Fred

[Dave5Cs]

I use Delo 100!....

[ol713]

Hi;
    I had 315 80x22.5 on the front of my mci.  It   made the speedo fast
    by about 3mph. I took them off because of age.  I am now looking
    for new ones.  Again I will use that same size because big trucks are
    using them and they are over kill for bus use, also  they are more avaliable
    than 12rx 22.5.  Best price I have found is $365 ea with 20 ply.  (china)
    Usually run good used tires on the drive,  but they are getting hard to
    find in either size.
    What part of the country are you in?
                                          Good luck.    Merle.                             
   

[Fred Mc]

Well, I live in Canada(near Vancouver) but am looking at some from Wash. Looking for ones with recent mfg. as my tires age out as opposed to wear out.

[chessie4905]

What is the vehicle? GMC's with automatics usually can't spare the loss of top mph with smalle drive tires. Also 315's are a little smaller in dia than 12.00's

[Fred Mc]

Its a GM PD 4106 with manual trans.

Thx

Fred

[HB of CJ]

I am not sure here.  Did the 12Rx22.5 require or desire a slightly wider rim width?  If memory serves, (always suspect) the wheels on my old 1974 Crown VIN 37317 had one half inch wider steel rims?  Some help please here.  Also, if true, does that imply or beg the question that a 11Rx22.5 may or may not need a slightly different rim width from that of the 12R?  Does it matter any?  Again, I do not know.  HB of CJ (Old Coot)

[RoyJ]

Its a GM PD 4106 with manual trans.

Thx

Fred

Is there a reason you're getting tire across the border? Son Tire in Burnaby has offered me decent prices on take offs in the past (I believe $160 for Michelin steers with half tread, I would age them out before wear).

I believe 11R22.5s should offer plenty weight capacity, but your revs will be higher on the highway. I got 11R24.5s for my drive axle (35' Prevost, 4.10 rear) to keep my revs reasonable.

On the front I'm running 315/80, but it's way overkill for my weight (3700 kgs). With my narrow rim (8.25") the tread is slightly bowed out, which I don't like. Next time I'm getting 11R22.5s.

[RJ]

Its a GM PD 4106 with manual trans.

Fred -

GM designed the powertrain, from engine to transmission to rear axle, around tires that turn 495 revs per mile.

So if you're looking at performance of your coach equal to how the factory designed it, then look for tires that come as close as possible to OEM revs/mile.

More revs/mile translates to lower top speed and greater fuel consumption.  Lower revs/mile vs OEM will give greater top speed and slightly better fuel economy.

You choose!

FWIW & HTH. . .

[chessie4905]

   If you go from 1200's to 295's you'll lose about 3 to 4mph top speed and 75 to 100 higher rpm's at your cruising speed.

[TomC]

The determining factor is the weight of the bus. Weigh your bus by axle. My guess is that you could use the 11R-22.5 (a very popular size) rather than the 12R-22.5 (a hard size to readily find). 315/80R-22.5 is a very heavy-duty tire that is WAY overkill for rear axle and expensive. 295/75R-22.5 or 275/80R-22.5 are the most popular tire size on trucks now. You have to decide if you can take the rpm difference between the tires that will make the engine run faster at cruise speed. In general-
11R-22.5 is 495-500rpm, 12R-22.5 and 315/80R-22.5 about the same at 485rpm, 295/75R-22.5 and 275/80R-22.5 are in the 509-517rpm range. Personally, 11R-22.5 14ply would be my choice with highway drive tire. Good Luck, TomC

[daddyoften]

This is something I have been pondering as well.  I have a 4107 that the PO installed a 77 engine and auto tranny in.  I drove it home and was able to pull 70mph for just a bit until the engine got hot.  I didn't have a tach so I have no idea how fast the engine was running.  The bus does have the 12 22.5's on it now but as everyone else is saying they are expensive and not as easy to find.  I have a chance to get 6 24.5 aluminum wheels lug centering for next to nothing.  What size tire of the 24.5's runs that magic 496 rpm's?

[Taibob]

Fred,
We just started to strip down a MCI 9 in Oliver BC.
We have good 22.5 tyres on it.
All other parts as well. [less motor]
Good seats, glass, etc.

Can arrange delivery to Langley or come here for a holiday.

Contact me. Info in profile or:
Bob Hutton 250-498-3269  taibob@persona.ca

[Darkspeed]

These are 11R24.5 43.5" Diameter 32/32 deep tread http://www.ebay.com/itm/4-Tires-11R24-5-New-GL266D-32-32-Rear-Deep-Drive-Truck-Tire-16-PR-11245-/191122773647

43.5 * 3.1415 = 136.65525

63360" in a mile

63360" / 136.65525 = 463.6 rev/mile

My GM is converted to Automatic trans - V730 so im looking for less rev per mile

Fronts > http://www.ebay.com/itm/2-Tires-11R24-5-GL116S-16-PR-Front-Steer-truck-tire-11X24-5-Radial-11245-/141486099943

[eagle19952]

Atleast they aren't Chinese...

These are 11R24.5 43.5" Diameter 32/32 deep tread http://www.ebay.com/itm/4-Tires-11R24-5-New-GL266D-32-32-Rear-Deep-Drive-Truck-Tire-16-PR-11245-/191122773647

43.5 * 3.1415 = 136.65525

63360" in a mile

63360" / 136.65525 = 463.6 rev/mile

My GM is converted to Automatic trans - V730 so im looking for less rev per mile

Fronts > http://www.ebay.com/itm/2-Tires-11R24-5-GL116S-16-PR-Front-Steer-truck-tire-11X24-5-Radial-11245-/141486099943