How much air pressure should you run in rear paddles???

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NOSJunkie
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How much air pressure should you run in rear paddles???

Post by NOSJunkie »

Have a SS6 w/4.3 liter V6 and a Magnum 44 transaxle, not sure how much it weighs (anyone that knows could you please let me know) , but what is the minimum PSI. you can safley run in rear tires???? thanks .... joe

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Post by Sandemon »

I would start with about 7 lbs and go from there. I run around 5 lbs in my ss6 but with a 2180 vw so it is a little lighter than yours. I woud not go less than 5 lbs without beadlocks. :twisted: 8) :)
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Post by mark harms »

Joe,

Even though I’ve retired from STU, I still remember one or two things about sand tires.

The old rule of thumb was never to run a tire so low that it would cause a wrinkle. When a tire runs that low it tears itself up from the inside out. Having said that before the advent of the long travel craze I use to recommend at least two pounds above where a wrinkle would just barely start. Even a tire not showing a wrinkle in a static position could wrinkle when you apply torque to the wheel. This was the reason for the extra two pounds.

In today’s world of huge wheel travel and mega-buck shocks, a buggy can almost fly until gravity hears about it. Now days we worry about bending wheels by not running enough air pressure. The short answer has more to do with how hard the driver is going to drive the car. A sand tire typically works more efficiently at a low pressure than a higher one. Now much comes into play here when we talk about air pressure, performance and sand tires, however to stay on topic squaring a wheel by have the ground compress the tire into the wheel is of a bigger concern today. Flying and landing hard or traveling at a high rate of speed over whoops with out enough air pressure will most certainly send you to the wheel store.

Joe there isn’t one pressure for everyone, however if you drive extremely hard start at 15 psi and if you drive moderately aggressively 10-12. If your car weighs in the 1500’s to 1800’s this should be a place to start. Keep an eye on your wheels and if you see any bending (usually on the inside if your running bead locks) add a couple more pounds. Also remember, if you drive at night check your pressure because as temperature drops so does air pressure unless your one of those guys that runs one of those exotic gases like nitrogen that’s not effected by temp. Oh by the way C02 is really bad on pressure when it comes to hot and cold temps. I hope this helps.

Mark

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Post by desertsteve »

JNJ- my rail weight is around 1400, rear eng and I love to dune hard. I never had any problems with my rear paddles untill I got in to the 7psi range. Now I have beadlocks @ 7psi and I'm not sure about the fine line!. I check air pressure on all 4's everyday. Sand tires have a tendancy to leak, so dont get lazy ! especially before a fast ride !!.

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Post by OBSESSED »

a SS6 w/4.3 liter V6 and a Magnum 44 transaxle, not sure how much it weighs
I am sure your rail's weight is very close to 1200 lb. With that trans and engine. A VW?VW with that frame comes in around 1000 lb.

So as the expert on tires says (Mark Harms) 2 lbs above the wrinkle.
OR more.....

I love to spin my tires and slide. My rail's weight is just under 1500 lb. I run between 8-12 lbs. I never have a wrinkle. I check the tires EVERY day. If it is hot out, I may let some air out. But since it's so fricken cold lately, 12 cold is still 12 after a 6 hour dune ride.

Remember each rail will have a different wrinkle factor.
My tires wil wrinkle at 6 lbs on my rail. But because my wife's rail's weight is only 1150 lb, my tires on her rail would wrinkle at maybe 4.5 - 5 lb.
I use the thumb test. (I have won $$$ also) Pump your tire to 10 lb. Push your thumb into the side wall. Feel it. Now let some out as you are pressing with the thumb. You can feel the difference between 8 lb and 10.

Watch your roost, and the others in your group. If you are throwing up more on the drivers side, the drivers tire is low.....

One time on a night ride, following a new group of duners, I told the guy in front of me, your drivers side roost looks like 4.5 lb and the pass side looks like 6 both maybe a little low for the type of duning we are doing.
He looked at me funny. When he got back to camp, he asked me how I knew? Exactly 4.5 and 6 lbs.......On his gauge. :shock:

Learn to feel it. 8)

Steve

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Post by NE14SAND »

Oh by the way C02 is really bad on pressure when it comes to hot and cold temps.
please explain this statement, i allways have and use a bottle. thank you
if the green cones are out all is good!!!!!!!!!!!!!!!

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Post by mark harms »

NE14Sand,

So have I.

Have you ever noticed how much more temp affects race fuel when stored in a plastic can than pump gas in the sunlight? It sort of works like that. I can’t pronounce the process properly let alone spell it.

C02 when stored is in a liquid and when the pressure is released it boils and that’s the pressure in gas form you put in your tires. When ambient temp drops the pressure in the bottle drops and when ambient temp rises so does the pressure.

A friend of mine has this airplane. He used C02 in his brand new tires and thought he had a hole in the tube. When he would arrive at the hanger in the morning when the ambient temp was low he found the tires appeared low. He removed the tires and checked them very carefully and couldn’t find anything wrong keep in mind these were brand new tires and tubes. He again put C02 in the tires and checked the tires with the correct pressure keeping in mind this is now late afternoon (ambient temp is up). He came back the next morning and his tires were low again. To make a long story shorter he was told not to use C02 by someone and when he used compressed air his issue was resolved.

All I can tell you is that gases like C02 aren’t as stable as others. There is one other thing you might want to look into and that is carbonic acid. With tire sealer in a tire and using C02 you might find the PH balance to go haywire. I’m not saying it will but could damage a very expensive set of wheels.

Try a little test by putting C02 in one tire and compressed air in the other and check your pressures periodically and check for a difference.

Mark

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Post by OBSESSED »

OR,
Find an inert gas that has a smaller molecule than the rubber on your tires….

Say what?

I had an AC contractor friend that ran FREON in his tires. He swore by it!

I never tried it, but you hear all kinds of stuff.

SB

BTW-No helium wont work, it'll leak out (bigger molecule), and it wont help you do a better wheelie either.

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Post by Virginsand »

Nitrogen is used in aircraft tires because it is inert and stable.

The down side to nitrogen is when it is stored it is still a gas and not a liquid, this limits the volume.

Incase of a fire, nitrogen will not feed a fire but help put it out if the tires burn.

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Post by mark harms »

Be careful about using any solvent-based chemicals in or on your tires. Petroleum products can break down the rubber compounds in tires. DO NOT use the stuff with the little Viking on the bottle. Use 303 Aerospace Protectant instead to keep the rubber in your tires from drying out.

Also one of the ways sand tires leak is by wicking through the cord. The air inside the tire can enter the cord anywhere and escape anywhere cord is exposed outside the tire. This is where a good tire sealer does the trick. One of the problems I’ve seen with some tires running bead locks with respect to leaking is the chafing. My understanding is that bead locks where designed for the sprint car industry originally. Sprint cars generally go through tires every race and chafing isn’t an issue. However sand tires might last a person ten or more years if he or she takes care of them. Having said that the slight design flaw I’ve seen with all bead lock manufactures is that they don’t radius the clamping ring like a wheel does. With a sharp edge against a tire like all the clamping rings have it doesn’t take long to expose the cord to the atmosphere and allow wicking to happen. This is a bigger problem with tires on too narrow of wheels. There is a wheel manufacture out there today that is aware of the problem and I’m sure you’ll see changes in the future.

Remember if you put strange gases in a tire that might have sealer in it, it could cause the PH balance to become corrosive to your wheels. Also there are many different tire sealers and it’s very important you don’t use one that doesn’t have the correct PH. I’m personally not a fan of Slime (the green stuff) for a couple of reasons. The sealer I had the best luck with and which I sold was made by Berrymans and called Seal-R. This sealer had the PH I was looking for and had good flowing characteristics. I would plug up the cord and stop the wicking.

Hope this tidbit of info helps.

mark

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Post by Intelliduner »

mark harms wrote:it’s very important you don’t use one that doesn’t have the correct PH. I’m personally not a fan of Slime (the green stuff) for a couple of reasons. The sealer I had the best luck with and which I sold was made by Berrymans and called Seal-R. This sealer had the PH I was looking for and had good flowing characteristics. I would plug up the cord and stop the wicking.
What is the correct pH? Where do you find the pH for these products? The website and MSDS for Seal-R doesn't list it.

_dennis

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Post by FunRunner »

Mark Harms:
One of the problems I’ve seen with some tires running bead locks with respect to leaking is the chafing.
that is the reason I tell people to run more air than what they might think would work best, especially in light of how hard the cars are run. I run 9lbs with my bead locks. I might think I could run less pressure because the b/l will keep the tires on the wheels; however, the chafing problem Mark mentions is a good reason to run a couple of lbs extra, minimum. Also, a slightly wider wheel would help that situation, because you don't have as much sidewall bulge, and that reduces the chafing some. That choice isn't available in all situations; In my case, I run 13 1/2 Douglas, because that is a wheel they have available. A radiused outer edge on the ring where it meets the tire would help. Something else I hear people saying is "I just add water to my sealant". I think you're asking for trouble doing that. The best thing to do is break the tires down, clean them out and put new sealant in once a season, or at least if it is detected the sealant isn't doing the job anymore; simply adding more sealant ceases to be effective as it can't get to some of the areas it should. Also, get in the habit of checking pressures, because as has been mentioned, tires will gain air in the heat and lose pressure over night. Oh, one other thing I have heard is guys who like to wheelie, tend to order larger paddles to aid that ability; then they let the tires down on pressure, which when high horsepower is applied, wrinkles the sidewall of the tire, and although it helps the wheelie artist do his thing, it puts the kiss of death on the tires; In that situation, the sidewalls are going to give out in a short period of time and the chafing is going to show up early on.
Last edited by FunRunner on Mon Jan 19, 2004 3:58 pm, edited 2 times in total.

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Post by NOSJunkie »

Where do you get Aerospace protectant 303?? Is that the brand name?? Joe

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Post by mark harms »

It’s been a long time since I dealt with the PH issue with respect a number. If memory serves me correctly I want to say somewhere around number six. The easiest way to find your particular number is to use litmus paper, which measures the PH level. I’m not sure where to find this paper however the Internet might be a good place to start. Another possibility might be to ask if we have any chemists in the bleachers.

When I serviced tires for customers I would dismount the tire, wash it out thoroughly, and let it dry completely before I remounted it. Roger alluded to the reason. Water will change the PH if added to a tire. Even some tire mounting lubes mixed with water can change PH numbers. When you use things like liquid dish soap or anything else with soap the PH will go nuts inside the tire. The sealer I sold depending the condition of the tire would last 1 to 3 years depending on how long the tire sat. The sealer I sold had a latex and glycol base and it was the fluid that carried the microscopic pieces of flock that would look for any small hole to plug up. If the tire sits for extended periods of time the sealer puddles in the low spot. Everywhere besides the puddle will dry to the inside of the tire over time and hold the microscopic particles of flock captive. What you end up with after time is a clear fluid without any fibers to do the plugging. When you start to see clear fluid coming out of the sidewall it’s telling you it’s time to service your tires. That’s also the time you want to inspect your wheels for corrosion. I noticed that tires serviced more often than not showed less evidence of corrosion. Think about changing sealer like you’re oil. Don’t just add more as needed to change it, but in fact remove and replace it.

Joe, I think I’ve seen it in PEP Boys however you can always find it wherever they sell inflatable boats like Zodiac’s. The fabrics they build these boats with are very sensitive to the wrong protectant. I’ve been using 303 since the 80’s

Dennis if you call Berrymans in Texas and ask for the PH number I’m sure they would help you. Sorry I don’t have the phone number.

mark

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Post by NOSJunkie »

A neutral ph is 7.0, you can buy paper test strips at your local pet store its for testing aqarium water. My tires are the shave type, you can see cords everywhere on the tire. So it makes since to me to run a sealant. What kind do you recommend?? Brand name?? Joe

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Post by Intelliduner »

mark harms wrote:Joe, I think I’ve seen it in PEP Boys however you can always find it wherever they sell inflatable boats like Zodiac’s. The fabrics they build these boats with are very sensitive to the wrong protectant. I’ve been using 303 since the 80’s
I called a few Pep Boys here in San Diego a while back when Mark recommended it previously, but they didn't carry it. I found a marine shop in Chula Vista that carries it, but that's a bit of a hike from where I live. I now see that they added a distributor just a few minutes from me in Spring Valley--woot! :D

You can search for a distributor near you at this page:

http://www.303products.com/main.php?inf ... ilersearch

_dennis
Last edited by Intelliduner on Wed Jan 21, 2004 2:46 pm, edited 1 time in total.

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Post by jhitesma »

As far as PH why not just measure the stuff when it comes out of the can?

You can find PH strips at homebrew and wine making stores, the pet stores already mentioned, and sometimes pool supply stores (though they normally use a liquid method for measuring PH now it seems.) I know northernbrewer.com has test strips in various ranges as well as a couple of electronic PH meters.

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Post by xjruss »

Intelliduner wrote:
mark harms wrote:Joe, I think I’ve seen it in PEP Boys however you can always find it wherever they sell inflatable boats like Zodiac’s. The fabrics they build these boats with are very sensitive to the wrong protectant. I’ve been using 303 since the 80’s
I called a few Pep Boys here in San Diego a while back when Mark recommended it previously, but they didn't carry it. I found a marine shop in Chula Vista that carries it, but that's a bit of a hike from where I live. I now see that they added a distributor just a few minutes from me in Spring Valley--woot! :D

You can search for a distributor near you at this page:

http://www.303products.com/main.php?inf ... ilersearch

_dennis

You should be able to find 303 Protectant at Camping World.
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