| Author | Message | ||
| s'COOL busnut Rating: N/A |
Does anybody have any experience with this? My brother-in-law wants to 'gear up' his bus to be able to increase top speed. He currently has 11.00 x 22.5 tires. Rather than the high cost of changing gears in the rearend, what can one expect to gain by going with taller tires? Right now his top speed is about 63 mph. Yes, he can pull stumps with his bus! (And he is aware that he will loose speed on the hills by putting on taller tires) What speed can he realistically expect to hit with taller tires? What size tires / wheels should he go with? Thanks for your wisdom! Mark s'COOL busnut | ||
| Stephen Fessenden (Sffess)
Rating: N/A |
By tire table an 11R22.5 is 503 revs per mile and an 11R24.5 is 480 revs per mile. 503/480 X 63mph yields an answer of 66 mph with the larger tire. Looks like you would have to go to a less common tire to go any fasterand it would have to fit your wheel well. | ||
| gusc Rating: N/A |
Check different brands of tires even though they are listed under the same size. Few brands are the same. Pick the one with the greatest rolling radius and then do the math Stephen showed above. Even better is to actually mount a tire on the bus, mark it with chalk and measure the actual rolling distance for one revolution. This method is the most accurate. Also, I think you will need a different wheel for the 11R24.5 tires. | ||
| Vin (Billybonz)
Rating: N/A |
Mark, There are lots of threads on tire size in the archives. Just click Search located to the left. There is a wealth of information listed there. Good luck, Bones 1973 GMC T6H4523 | ||
| R Swanson
Rating: N/A |
You could go to 12R 22.5 tires which would give an extra 2 to 3 MPH only. They are not as common as 11R 22.5 size and likely a bit more expensive. If you want 11x24.5 size you will of coarse have to replace the wheels and tires on at least the drive axle. | ||
| s'COOL busnut Rating: N/A |
Thanks, guys Stephen, Where did you get the tire table you're using? Bones, yes, I spent quite a bit of searching @ the archives. I didn't find any actual mph 'gain' reported by anyone. Anybody else...? thanks mark s'COOL busnut | ||
| Stephen Fessenden (Sffess)
Rating: N/A |
I just did a search for semi truck tires and found it. I don't have it bookmarked. A tire store will also have a table that lists overall diameter and revolutions per mile. Either will work in the equation. | ||
| Brian (Bigbusguy)
Rating: N/A |
Look here on the left is a link to a MPG table. http://www.freewebs.com/darisb/ Brian 4905 Klamath Falls Oregon | ||
| Brian Brown (Fishbowlbrian)
Rating: N/A |
Recently, RJ mentioned that he'd found a Bridgestone 11R24.5 drive tire that'll do 470 revs/mile. Maybe 44.5" dia. or so. That's the tallest bus tire I've seen. This might buy maybe just 5mph, per Daris' calculator. It must be a transit bus. Do you know the make? You can go to the Websites of Michelin, Firestone, Bridgestone, etc. and readily get tire dia. data online. Brian Brown PD4106 | ||
| Sean Welsh (Sean)
Rating: N/A |
The Bridgestone M843 turns 468 in that size, and is speed-rated for 65. The M726EL turns 470 and is rated for 75. But this seems to me to be a high price to pay for minimal gain. In order to use any of these tires, you'd have to change wheels from the current 22.5's to 24.5's, to gain perhaps 20 revs/mile. Carefully choosing among available 11R22.5 models will probably yield 3-5 revs/mile over whatever he's got now, and going to 12R22.5 (assuming he's got 8.25" wheels) would probably get him 13-16 r/m. None of these is going to provide remarkable results. In the best case, going to the 24.5 wheels will take him up to maybe 65 or 66 mph, as already noted. Now, if he already needs new tires, and he can get a deal on six 24.5 wheels, or pay the difference for 12R22.5s, then this is probably a cheap way to get another 2-3mph, but I'm guessing he's really hoping for something more impressive. -Sean (who just spent two weeks shopping for tires and wheels) | ||
| Stan Rating: N/A |
From the information that comes up on this board it appears that the cost of tires and wheels is about the same or less than the cost of a set of gears. If a complete used carrier assembly can be found for your bus it would be an easy change and cheaper than changing tires and wheels. | ||
| John Rigbyj
Rating: N/A |
What Model bus do you have? Maybe the diff approach could be acceptable If we new the bus. John | ||
| Craig (Ceieio)
Rating: N/A |
Here's the math on rev's per mile if you want to make a spreadsheet or calculator... In one revolution, the bus travels the circumference of the tire (pi * d) where d is actual diameter or height of the tire in inches. So the revolutions / inch is 1 / (pi * d). Now to convert the inches to something more interesting, like miles. 12 in. per foot * 5280 ft per mile = 63360. So revs / mile = 63360 / (pi * d) or 63360 / (3.14159 * d) simplified to 20168.13 / d Revs/Mi = 20168.13 / d Now one thing to consider is the loaded height at pressure and with a bus sitting on top of it. It may lose a little height in sidewall bulge. | ||
| TWODOGS (Twodogs)
Rating: N/A |
here is another formula...city bus/school bus = stay off interstate | ||
| John that newguy Rating: N/A |
I dunno... I remember back in the 60s, bringing the Eagle into the Trailways garage (like the rest of the guys did) and tossing the guy 20 bucks to tweak the governor up a couple.. Has this become some sort of an impossible task lately? Or are too many bus nuts worrying too much about turning up the governor higher than it already is? You should be able to do 55 in third; I never drove a bus (charter or line) that didn't. That would equate to a damned decent highway speed in 4th. | ||
| TWODOGS (Twodogs)
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come with me on the Eagle...I'll make ya' wet your pants  | ||
| John that newguy Rating: N/A |
I do that anyway. | ||
| TWODOGS (Twodogs)
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................ | ||
| sCOOL busnut Rating: N/A |
Two Dogs You're a dork ........[INSERT SMILEY FACE] | ||
| Johnny Rating: N/A |
I don't know, 2D...my long-nose Ford B-700 has no trouble running 75MPH. It had plenty of power & RPM left, too...my 460 wasn't even spinning 3000RPM. |