Tire pressure opinions.

mEl

Well-known Member
Location
NC PA.
Fellow pullers,

Mel from NC Pa here, I pull in the light 3.5 MPH Cut tire classes here, 45-5500 lbs, 45 not our best because of front end issues as we have no movable weight at that weight, I have 15.5 x 38 Double cut BFG tires, 20 High x18 Back drawbar. Looking for some wisdom on tire pressure, we pull on a heavy clay track that takes a lot of power, when the track is right my tires are very good and some days very hard to beat, other days just average, Power is not an issue, just looking for some opinions to chew on, have been at 5-5.5 lbs and moved up to 7 last pull, did ok , 2nd in 5. thanks in advance for your input!
 
Were I you, I'd have a pal watch my sidewalls next pull to see how much your tires squatted and wrinkled under a
load. I personally ran a number of that size tires and usually at around 9 lbs. My experience was that the wider
your rims were to tire width, the more pressure you could run. The ideal, to me, is for the surface of the tire to
be flat/flush with the track for optimum bite. I liked for my rims to be as wide as rules allowed and run as much
air as I could in order to keep the tires from squatting down and costing me drawbar height. I also think that as you move up in weight class you might consider adding a tad of air to them per class. I always found that every 1/2 or 1/2 percentage point seemed to matter. gm
 
Thank you all for your input, the tires are 15.5 x 38 on 16" rims, I will put a pic up if I can.
mvphoto97817.jpg
 
Do you use a pressure equalizer hose between two tires 15 minutes before you pull?

Good point the others made ,you park one tire in sun and the other shaded ? Everything has a bearing on gription.

I dont Rinkle my side walls of my tires . 14 to 16 psi using a moroso low pressure tire gage that way I get maximum downforce off the chain .

I run 8 ply
 
hav e not used an equalizer hose but from watchin the TPMS system on my car I see where you are coming from and they are a lot smaller tire!
 
I have noticed that as the track (air temperature) goes up (or down)so does air pressure . (So)Fifteenth minutes before staging I adjust the
pressure to what I call optimum. I have noticed that one tire seems to be more easy to deformed with thumb pressure . I aways wonder what
going on . How can I understand how much this hurts the performance.

That side I would give it a half pound more air .

I alway wanted to use the durometer gage to measure and see if it was environment (sun) or tire material composition.

I never bought one but if I was serious ,I would do it . Just see if Im right or wrong. The only thing I would was as I pulled away from sled I
would examine the right and left wheel track to make sure they are equal.
 
I will definitely work on those issues next pull, I want to move the battery front to help weighting for 4500. keeping the front down in that class is an issue, not my best class, pulls better heavier. Have a lot of fun with it though win or lose. Took it to the S Va winter classic in Va. this spring as my brother moved down there, didn't win much but ended up in a couple pull offs, not bad with 45-50 tractors in a class. just for kicks we entered into a 8 MPH class just because we were there, ran 2nd gear, got 7.3 MPH but ran down pretty good at the end. was very pleased.
 
Power is always a issue. That is
controllable power. In a mph classes the
one that can stay closest to the maximum
for the longest time will have the best
chance to win. Buddy of mine won this
summer with his drawbar set at 18 instead
of 20. This Summer I won the 4000 6mph
with my D17. No movable weight except
moved both batteries to front. Let my
drawbar down a 1/2 and moved wheelie bars
as low as possible. It hooked up and just
kept letting off throttle till it died.
Front was up about 6 ft.Pulled 4500 6 mph
and then 8 mph later. Managed to win both.
Had different strategie had drawbar at 20
and went as fast as possible. Then 2 weeks
later thinking I was a pretty good tractor
puller pulled 4250 6 mph got 3rd out of
7. Then pulled 4500 6 mph. Got 7th out of
7. Front was weighted same as 4250 but by
then that was to much. So I did worse than
anyone there. So no one knows how much air
to put in their tires every time.
 
if you are going to make a mistake on tire psi . Better 2psi too high Vs 2psi too low .
The loss of drawbar height from squatting tires robs distance .
 
Guys, had our first pulls since my original post and I went to 12 lbs pressure, my driver said it felt more hooked, we got a couple seconds and a third with the 39 but there was a very strong M and some very tough As. The M was able to run a higher gear at fairly low RPMs to stay under 3.5. The JDs have good power also but the DC is a 39 and geared faster than later DCs in low gear, 11-1200 is all I can run without speeding and have good reserve above that if needed. I am sure that the M has double my HP but I am running off the shelf sleeves and pistons, M&W design and had Charlie at Cam crafters make me up a cam. Pretty much a stock engine in comparison to what I am running against. WIll continue next year to see what we need to do, closed out the season here yesterday. Good to see you post B&D hadn't seen you for a while.
 


Fellas, thanks for your input on the tire pressure help on my 39 DC, Just sharing our year results with you and hope to use your good advice going forward to next year. Posting points results for last year, very good year for us Cases considering we are running against some Baker stuff and stuff brought in from the midwest and tractors travelling from NY, NJ and W VA, names you would know
mvphoto99366.jpg
 

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