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Over the past few years, I've run a lot of different paddle combos on 4 different quads. I was looking through some picture files I had on my PC and figured some of you could use some help getting a visual on sand tire Roll outs and width. :D

First and most important is that what ever written or chalked on the side of your tire (ie. Skat Trak chalks a # usually 60 to 72) is not necesarily the correct rollout. :huh: The size of the rims you use, the tire pressure, temperature, the manufactuers tire carcass design, and the number of buffs (ie. single buff, B-to-B buff, triple buff, comp cut etc) all affect the footprint and the overall diameter of your sand tire.

The rollout needs to the calculated based on the tire carcass, not including the paddle. There are two fairly easy ways I measure rollout:

(1) Take the sand tire (by itself) and slowly roll it across flat, smooth sand and pay close attention to when 1 revolution is complete, then pick up the tire - and measure the distance from start to end. You have to be careful when you start and stop the roll and go in a straight line and be precise. :first:

(2) Another way is to take a paddle that is aired up (by itself) and place it on a hard surface such as your garage floor with the carcass (not paddle) touching the ground. With the paddle tire perfectly perpendicular to the ground, take an adjustable T-stick and measure the ground to the top of the tire carcass-only. Then measure the length in inches, and multiply by Pi (ie. 3.14) to get the rollout. :second:

What you'll probably find is that your 21" tire is really not a true 21" and rather 20.5" etc. :eek:

Some things are pretty consistant: if you widen your rim width, you will also create a flatter profile (ie. less donut shape) and smaller diameter (ie. less rollout). Lower tire pressure reduces the static rollout of your tire, and definitely changes a paddle characteristic in the sand - there's a huge difference in running 3lbs air vs 5 lbs air.

Another thing, is if you go from an 8x8 rim to an 8x7 rim, the thinner rim width squeezes in the tire, resulting in a balloon-shaped tire, increasing the diameter by about 3/4ths of an inch = an addtional 2-3 inches in extra rollout.

So here's some pictures I had of some different paddle tire and rim combos to give you an idea of some combo's. I've had more combos, but I can't find all of the pictures over the years...

(Left to Right)

(1) 21x12x8 Skat Trak 6-paddle Extreme (chalk=67) on 8x8 rim vs. 21" STU Padla Brat on 8x7 rim vs. a 20" ITP Sand Star on 8x8 rim


(2) Same tires again, this time from tallest to shortest (left to right) Skat vs. STU vs. Sand Star


(3) This picture is the same 21x12x8 Skat 6-paddle Extreme (chalk=67) on an 8x8 vs. a 20x11x8" Skat 8-paddle on an 8x8 (chalk=64)


(4) This picture is a 21x12x8 Skat 6-paddle Extreme (chalk=68) on an 8x7 vs. 21" STU Brat on an 8x7


(5) This picture is a 22x11x8 Skat 7-paddle Hauler (chalk=70) on an 8x7 rim vs. a 21x12x8 Skat 6-paddle Extreme (chalk=68) on an 8x7


Whats interesting about picture #5 is that I had the 22" on an 8x8 rim first (I can't find the picture) and it was nearly identical in height and width as the 21" Skat Extreme (chalk=68) on an 8x7". But when I changed out the 22" skat from an 8x8 to an 8x7 rim, it narrowed the tire alot and increased the height by 1" = +3" more rollout. BTW - haven't run the 22" on an 8x7 at the dunes yet, but it will probably be more of a hill set up than a duning set up.

At the end of the day, in-glamis, my favorite "bang-for the buck" and "works great in any sand condition" set up on the 450's has been the 21x12x8 Skat 6p Extreme with a chalked 68 rollout, on an 8x7 rim :blink:.... BUT - the Brats are about 1 length quicker up the hill for me AND double the price...

BTW - there is another factor to rollout, but I won't get into it - and that is the dynamic rollout of a paddle tire as wheel speed and revolution increases and the tire spins quicker, it increases the diameter - and different rubber compounds and ply thickness affect this... :stars:
 

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<div class='quotetop'>QUOTE (Vader @ May 11 2008, 01:52 AM) <{POST_SNAPBACK}></div>
Over the past few years, I've run a lot of different paddle combos on 4 different quads. I was looking through some picture files I had on my PC and figured some of you could use some help getting a visual on sand tire Roll outs and width. :D

First and most important is that what ever written or chalked on the side of your tire (ie. Skat Trak chalks a # usually 60 to 72) is not necesarily the correct rollout. :huh: The size of the rims you use, the tire pressure, temperature, the manufactuers tire carcass design, and the number of buffs (ie. single buff, B-to-B buff, triple buff, comp cut etc) all affect the footprint and the overall diameter of your sand tire.

The rollout needs to the calculated based on the tire carcass, not including the paddle. There are two fairly easy ways I measure rollout:

(1) Take the sand tire (by itself) and slowly roll it across flat, smooth sand and pay close attention to when 1 revolution is complete, then pick up the tire - and measure the distance from start to end. You have to be careful when you start and stop the roll and go in a straight line and be precise. :first:

(2) Another way is to take a paddle that is aired up (by itself) and place it on a hard surface such as your garage floor with the carcass (not paddle) touching the ground. With the paddle tire perfectly perpendicular to the ground, take an adjustable T-stick and measure the ground to the top of the tire carcass-only. Then measure the length in inches, and multiply by Pi (ie. 3.14) to get the rollout. :second:

What you'll probably find is that your 21" tire is really not a true 21" and rather 20.5" etc. :eek:

Some things are pretty consistant: if you widen your rim width, you will also create a flatter profile (ie. less donut shape) and smaller diameter (ie. less rollout). Lower tire pressure reduces the static rollout of your tire, and definitely changes a paddle characteristic in the sand - there's a huge difference in running 3lbs air vs 5 lbs air.

Another thing, is if you go from an 8x8 rim to an 8x7 rim, the thinner rim width squeezes in the tire, resulting in a balloon-shaped tire, increasing the diameter by about 3/4ths of an inch = an addtional 2-3 inches in extra rollout.

So here's some pictures I had of some different paddle tire and rim combos to give you an idea of some combo's. I've had more combos, but I can't find all of the pictures over the years...

(Left to Right)

(1) 21x12x8 Skat Trak 6-paddle Extreme (chalk=67) on 8x8 rim vs. 21" STU Padla Brat on 8x7 rim vs. a 20" ITP Sand Star on 8x8 rim


(2) Same tires again, this time from tallest to shortest (left to right) Skat vs. STU vs. Sand Star


(3) This picture is the same 21x12x8 Skat 6-paddle Extreme (chalk=67) on an 8x8 vs. a 20x11x8" Skat 8-paddle on an 8x8 (chalk=64)


(4) This picture is a 21x12x8 Skat 6-paddle Extreme (chalk=68) on an 8x7 vs. 21" STU Brat on an 8x7


(5) This picture is a 22x11x8 Skat 7-paddle Hauler (chalk=70) on an 8x7 rim vs. a 21x12x8 Skat 6-paddle Extreme (chalk=68) on an 8x7


Whats interesting about picture #5 is that I had the 22" on an 8x8 rim first (I can't find the picture) and it was nearly identical in height and width as the 21" Skat Extreme (chalk=68) on an 8x7". But when I changed out the 22" skat from an 8x8 to an 8x7 rim, it narrowed the tire alot and increased the height by 1" = +3" more rollout. BTW - haven't run the 22" on an 8x7 at the dunes yet, but it will probably be more of a hill set up than a duning set up.

At the end of the day, in-glamis, my favorite "bang-for the buck" and "works great in any sand condition" set up on the 450's has been the 21x12x8 Skat 6p Extreme with a chalked 68 rollout, on an 8x7 rim :blink:.... BUT - the Brats are about 1 length quicker up the hill for me AND double the price...

BTW - there is another factor to rollout, but I won't get into it - and that is the dynamic rollout of a paddle tire as wheel speed and revolution increases and the tire spins quicker, it increases the diameter - and different rubber compounds and ply thickness affect this... :stars:[/b]
hey bro great info you just made my day you say the brat 21 on a 8+7 is faster then the skat 21 on a 8+7 wheel too is there any down side to brats besides the prize thanks bro
 

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Discussion Starter #6
<div class='quotetop'>QUOTE (jose1510 @ Jun 18 2008, 01:40 AM) <{POST_SNAPBACK}></div>
hey bro great info you just made my day you say the brat 21 on a 8+7 is faster then the skat 21 on a 8+7 wheel too is there any down side to brats besides the prize thanks bro[/b]
Down side to the brats besides price is that comp cuts slowly leak air (can be fixed by sealant, though) and they are usually 65-66" rollout, which is a good duning rollout but for hillshooting more rollout would be nice.
 

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<div class='quotetop'>QUOTE (Vader @ May 10 2008, 07:52 PM) <{POST_SNAPBACK}></div>
BTW - there is another factor to rollout, but I won't get into it - and that is the dynamic rollout of a paddle tire as wheel speed and revolution increases and the tire spins quicker, it increases the diameter - and different rubber compounds and ply thickness affect this... :stars:[/b]
Vader you have very good info and i would just like to add a bit about the dynamic rollout. For all intents and purposes the dynamic rollout of paddle tires on an atv can be neglected because it is only the 1st two gears that you would have a chance of generating the necessary acceleration force to spin the tire fast enough to cause it to balloon outward, and really the effect in 2nd gear will not be anywhere close to as noticeably in 2nd gear. How long can you even use first gear? it's a very short time and will probably only make a difference if you have two identical bikes with two identical riders. Also, from 3rd gear on up atv's just do not make enough horsepower and torque to make this worth worrying about.

On the other side, it would be possible to achieve a very noticeable dynamic rollout compared to stock rollout by running very thin sidewall tires and very low air pressures, though it's not recommended because of other obvious detrimental effects.

Not trying to proof any of your info wrong, i agree 100% with all you've said, just wanted to elaborate a bit on that stuff so that people aren't freakin out about it and losin sleep trying to figure out there rollout.

sorry for the rant i'm tired and off to bed.
 

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your way off on that one...about the rollout not being affected at higher speeds
 

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<div class='quotetop'>QUOTE (08LTRSMOKINYOU @ Jun 18 2008, 09:30 PM) <{POST_SNAPBACK}></div>
your way off on that one...about the rollout not being affected at higher speeds[/b]

that is very possible, but i do that that with stock transmission gears and stock sprockets, if the motor is spinning at 9500 rpm the rear tire is spinning at ~1420 rpm in 5th gear, and for that motor rpm the tire rpm is gonna be lower for every gear below 5th, and have a 13t front sprocket will make the tire rpm lower as well. 1400 rpm just doesn't seem like alot, though this doesn't take into account to forces from accelerating to that speed because determining an accurate angular acceleration of the rear wheel would suck.

all in all what i'm trying to say is to either side of this with a grain of salt because there are so many variables.
 

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its not really about the rpms that is makin the tire balloon out...its the speed that the tire is spinning...at 20 mph the rollout will be less then when at 60mph...someone correct me if im wrong...but im pretty sure this is how it works...
 

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that's 100% correct, i was just using the rpms as an example instead of the linear speed. 1420 tire rpms is ~75 mph with 18 rear wheels, or 84 mph with 20" tires (neglecting all fricational effects), which the 20" would have more dynamic runout with the same size rims, or if you put larger rims on the 20's than the 18's you could theoretically get the same additional runout over the static measurement for each size.

anyways, sorry if my wording isn't coming across very well, i'm not trying to dispute anything that's been said...
 

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I would have liked to see the PSI given for each tire variation given. You can manipulate to a certain extent the rollout from 2-4 PSI w/out stressing the sidewalls too much. Just a variable that I feel should have been given.

Great Info Vader and great clarrification Kojimep :tups:
 

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<div class='quotetop'>QUOTE (Vader @ Jun 18 2008, 11:56 AM) <{POST_SNAPBACK}></div>
Down side to the brats besides price is that comp cuts slowly leak air (can be fixed by sealant, though) and they are usually 65-66" rollout, which is a good duning rollout but for hillshooting more rollout would be nice.[/b]
What about for drag's (Pismo drag), would a Skat with a higher RO have the upper hand on the Brats 65-66 RO? Doesn't Fullerton or one of the tire places, do something to the Brat that gives it a higher RO? I weigh in a heavy 240lbs if it makes a difference, which Im sure it probaly will.
Thanks
<div class='quotetop'>QUOTE (AOLTR450 @ Jun 18 2008, 01:00 PM) <{POST_SNAPBACK}></div>
So much info I don't think I'm ever going to buy paddles, there's too many variables and opinions! :stars:
Someone just tell me what to buy!! :suicide:[/b]
I hear you. lol
 

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i've been thinking about placing a basic model of a tire in a FEA program to see what that gives me for the approximate dynamic runout, i know they can do rotational speed input, and possibly rotational acceleration as well. i'll have to try contacting one of the companies like skat to see if they could give me approximate values for the young's modulus and poisson's ratio of the material they use in there tires, which i'm sure they won't be too eager to share lol. still though, even with rough estimates it could be useful.

if it goes well i could then do more detailed models of the tires for more accurate results, would be fun to do in any case.
 

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I think vaders info was all anyone on here really needs to go by, we are all different weights, riding experience, so going into that much detail wont make to much difference playing on the hill or drags. if we all where running on actual drag strip with lights and timers, it would probably be a different story.. just my 02.....
 

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Discussion Starter #18
<div class='quotetop'>QUOTE (Jaydoggg @ Jun 19 2008, 09:59 AM) <{POST_SNAPBACK}></div>
I would have liked to see the PSI given for each tire variation given. You can manipulate to a certain extent the rollout from 2-4 PSI w/out stressing the sidewalls too much. Just a variable that I feel should have been given.[/b]
I run all my paddles between 5-6 psi, so that is the range in all the tire pictures

<div class='quotetop'>QUOTE (LS1LTR @ Jun 19 2008, 06:43 PM) <{POST_SNAPBACK}></div>
What about for drag's (Pismo drag), would a Skat with a higher RO have the upper hand on the Brats 65-66 RO?[/b]
As mentioned, testing different paddles with your own weight/quad is the only BEST way to set up your duner. I paddle for a combo general duning (w/ hills & bowls) and moderate hill-shooting/racing. I don;t ride at Pismo, but at Glamis, I only run the gecko flat drags every once in a while. The Brats do a great job of getting out of the hole at the beginning of the Gecko sand drags (loose / rutted sand) for sure.
 

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<div class='quotetop'>QUOTE (Vader @ Jun 18 2008, 07:56 PM) <{POST_SNAPBACK}></div>
Down side to the brats besides price is that comp cuts slowly leak air (can be fixed by sealant, though) and they are usually 65-66" rollout, which is a good duning rollout but for hillshooting more rollout would be nice.[/b]
thanx for the respond bro hey i was told that the brats are not made for jumping at all is that true if thats the case then i would go with extreams with a 68 roll out now some people are useing a 8+8 wheel but what ive read 8+7 seems better what do you think i just dont want to buy the wrong set of paddles thanks for all your help .
 

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my 20x10x8 Skat Trak Extremes are a 60.5" rollout. a rather small tire. i am going 14 48 gearing.
 
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