Author Topic: 13' tire/ 41' roll vs 16' tire/50' roll  (Read 4748 times)

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Offline crazycraftsman

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13' tire/ 41' roll vs 16' tire/50' roll
« on: November 12, 2015, 03:36:25 pm »
Im changing my tires from 13/6' rim - 16'/8'rim to make the uslmra rule in the classes i'll be running. Is there a big increase in speed with the 9' longer roll out? Thanks
owen
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Offline PJG56

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #1 on: November 12, 2015, 05:57:04 pm »
If you don't change your gear ratio there will be!!!!!!
Paul Guptill  (oppy) #238modX
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Offline crazycraftsman

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #2 on: November 12, 2015, 08:45:14 pm »
Never ran the big tires before and I'm going to have to basically start all over. I run the peerless 400's and I'm trying to stick with the same pulley setup for small and big tracks and just change sprockets just like you guys and gals do with the 700's. I ran 6.5 - 5 on small tracks and 8-5 on big tracks with either a 24 or 26 tooth trans sprocket . Would be nice to just change sprockets . I don't know the difference in speed/rpm 41" tire roll vs 50". I will write my old ratios if someone could help me figure out the ratio(mph) with the different tire size that would be awsome!! I'm not that great with math. Lol
owen
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Offline chavez

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #3 on: November 12, 2015, 10:36:34 pm »
Play with your tire diameter and rpm on this: http://www.eccarburetors.com/technical_14.html
Travis Callaway

Offline crazycraftsman

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #4 on: November 13, 2015, 12:05:32 am »
Unfortunately it doesn't work for the peerless 400 and doesn't show all the math involved.( different crown and piƱon count and larger sprocket on trans.
I have
8" engine pulley 5" trans
26 tooth trans sprocket 44 tooth rear
Crown is 33 teeth and 13 pinion
1st 39/16
2nd 34/21
3rd 30/25
7000rpm
My 16" tire has a roll out of 50"
Can someone please show the full math
Equation to figuring my mph in each gear.
This stuff fries the last bit of brain cells I have left so any help would be greatly appreciated!!
Once I have the math I can figure out the difference from my 41" to 50" tire roll in 2nd gear.
Also if I can get a middle spot by running a 7" engine pulley then just change sprockets instead of full pulley and belt swaps
owen
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Offline Mudgutts

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Re:
« Reply #5 on: November 13, 2015, 01:50:39 am »
I sort of copied EC's calc into MS excel to understand the math. So with your specs, I'll work it out for you tonight and try to post it all for you to understand.
So much maths to get there though. Lol

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #6 on: November 13, 2015, 05:44:18 am »
Granted, it was with a 700, but I went from 13" rears to 16" rears on a chassis. The only change I made was a 12 tooth on the trans with the 16's, vs a 15 tooth with the 13". All else 8" to 5" pulley remained the same.
Ed King

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Offline George Herrin

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #7 on: November 13, 2015, 06:37:28 am »
yup drop 3 teeth on trans you are there.
George Herrin #6
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Offline crazycraftsman

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #8 on: November 13, 2015, 10:26:45 am »
Thanks for the info Ed and George. Thought it would of been a bigger differance . I would really like to figure out the math lay out so I can see changes with pulley sizes and sprocket sizes.(2) so I don't have to ask again, because I know it's a pain.(3) So I'm able to fine tune stuff better. I ran 2 mowers last year with two different pulley combos so I had 8 belts(200)bucks . (1) back up belt fur each combo.I would be nice to cut that in half with one pulley set and make some smaller sprockets . Thanks for any help
owen
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Offline stvn_VA

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #9 on: November 13, 2015, 10:09:18 pm »
I have a excel spreadsheet with all that and the ability to change the gears for the 350/400s.    I have it on my work computer and I'll try to remember to send it to you.   I run the same tranny you do and you've helped me out with mine.
Steven
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Offline crazycraftsman

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Re: 13' tire/ 41' roll vs 16' tire/50' roll
« Reply #10 on: November 13, 2015, 11:45:08 pm »
Thanks that would be awsome Steven!! If you could email me ,that spreadsheet  would be sweet.
Owengrahn@gmail.com
owen
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