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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: edvanland on February 14, 2017, 09:37:33 AM

Title: Air Pressure
Post by: edvanland on February 14, 2017, 09:37:33 AM
Suggestions on air pressure. Tires are Yokohama 11R/22.5
front axle is 10860 drivers and tag are 23860 total weight is 33860
Currently running 110 PSI in front and 100 PSI in rear should I change or is that good.
Rides good and tires are wearing good now.
Thanks
ED
Title: Re: Air Pressure
Post by: Lin on February 14, 2017, 10:16:12 AM
There should be a tire pressure chart available online for the specific model tire you have.
Title: Re: Air Pressure
Post by: luvrbus on February 14, 2017, 11:47:18 AM
That is a small tire for a MCI 7 I think your pressures are about right,I wouldn't worry about it tires wear better and last longer with higher pressure according to the manufactures 
Title: Re: Air Pressure
Post by: Timkar on February 14, 2017, 01:47:48 PM
https://www.yokohamatruck.com/commercial/tire-tools (https://www.yokohamatruck.com/commercial/tire-tools)
Title: Re: Air Pressure
Post by: PP on February 14, 2017, 03:43:30 PM
Timkar, thanks for the handy chart calculator. I've always just ran all my tires at 100psi (12R-22.5) but according to the chart I need to up the fronts to 110psi. Even though it says I can lower the rears, I'm keeping them at 100psi.
Title: Re: Air Pressure
Post by: Zephod on February 14, 2017, 05:02:28 PM
My fronts are 10R22.5 and are supposed to be 95psi
The backs are supposed to be 10R22.5 and 85psi

The backs are actually 11R22.5 at 85psi.

According to my calculation, the 11s give me about 3mph extra speed over what the speedometer says.


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Title: Re: Air Pressure
Post by: Ed Hackenbruch on February 14, 2017, 08:00:39 PM
Keep in mind that after just a few miles down the road your tires will heat up and the air pressure will increase by about 10-13 percent. 
Title: Re: Air Pressure
Post by: luvrbus on February 14, 2017, 08:27:19 PM
Quote from: Ed Hackenbruch on February 14, 2017, 08:00:39 PM
Keep in mind that after just a few miles down the road your tires will heat up and the air pressure will increase by about 10-13 percent.  

Yep but a tire with almost the maximum air pressure won't heat up like a low inflated tire,I saw that test at the Bridgestone testing track in West Texas
Title: Re: Air Pressure
Post by: Zephod on February 15, 2017, 06:49:49 AM
Quote from: luvrbus on February 14, 2017, 08:27:19 PM


Yep but a tire with almost the maximum air pressure won't heat up like a low inflated tire,I saw that test at the Bridgestone testing track in West Texas
Years ago I saw somebody towing a car with an almost flat tire. You could smell the hot rubber many yards away and see smoke too.


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Title: Re: Air Pressure
Post by: TomC on February 16, 2017, 10:21:12 PM
You have the weight of the front axle-so you can run the exactly correct tire pressure. Weigh your drive axle and tag separately so you can get a load on each to also find out the exactly correct tire pressure. Guessing and running too high a tire pressure, reduces the tire foot print on the road (less traction) and gives a harder ride. Correct tire pressure will give you a very smoooooth ride. Good Luck, TomC
Title: Re: Air Pressure
Post by: Lee Bradley on February 16, 2017, 11:15:00 PM
Quote from: Ed Hackenbruch on February 14, 2017, 08:00:39 PM
Keep in mind that after just a few miles down the road your tires will heat up and the air pressure will increase by about 10-13 percent. 

But guide said  'Results are minimum recommended inflation pressures. Recommended PSI are for cold tires; never adjust inflation pressures for hot tires.'
Title: Re: Air Pressure
Post by: Ed Hackenbruch on February 17, 2017, 09:34:15 AM
Lee, the point i was trying to make was that if you set your tire pressure at say 90 lbs cold, you will be up to about 100 lbs a few miles down the road. Nothing wrong with that. Now like Clifford said an under inflated tire will heat up a lot more than a properly inflated tire....and that will cause tread and sidewall problems. If i remember right a tire that is run at 25% less than the maximum cold tire pressure is considered under inflated. A lower psi will give you a softer ride but will take more to get it down the road due to resistance, and will wear faster too. A higher psi will roll easier, which will give you better mpg, will wear better, (usually), but may give you a harder ride. Everyone needs to figure out what works best for them.  ;D  And the only time you adjust pressure for a hot tire is when you see that it is obviously too low....and if you have to do that, you want to recheck the tire after you get somewhere and let it cool down completely. 
Title: Re: Air Pressure
Post by: Lee Bradley on February 17, 2017, 09:50:52 AM
Not trying to pick a fight and I don't think you took it that way.  :D

Tires that are at a higher pressure are more resistant to hydroplaning.