Question on tire footprint?

Have a question on tire footprint.   Went to a pull today and did fairly good, but all of the pullers that did better then me had 38" tires compared to the 28" tires on my 45 diesel.   I was wondering if there was a footprint chart that told the differences between tire sizes and how much tire was on the ground at any one time.  For instance, if I took off the 14.9 x 28 tires that I have on right now and went to 13.6 x 38, would I be better off, or would I have to go to a 14.9 x 38?   This pull was kind of loose on tire size, and there was one tractor in our class, a WD that had I think 16.9 or 18.4 x 26 tires on it.   Most of the other pulls I go to, they limit width to 14.9 or 16.9 in the upper classes, or say to stay with the stock width that was available on the tractor. 

Was this a loose gravel track or a hard pulling power sucking black dirt or sticky clay track?If you are choosey on your tracks you'll place a whole lot easier. Deere pullers love the loose gravel tracks cause they don't have the power to compete on hard pulling ones. I'm talking strictly stock not stock appearing like some clubs accept as stock.

Edited by Lonn - 12 Sep 2010 at 8:55pm

13.6 x 28 (110 sq inches)....14.9 x 28 (145 sq in)....16.9 x 28 (175 sq in)...13.6 x 38 (165 sq in)...14.9 x 38 (200 sq in)....15.5 x 38 (180 sq in)....info taken from Firestone tire chart....footprint isn't everything......low gear is faster with 38"s and that is a good thing if you got enough HP.

A 15.5 x 38 is considered a "low profile" tire and just simply has less sq inches and is not as tall as a 14.9 x 38........16.9 x 34 has 220 sq inches.

Thanks DrAllis,
My 180D had 18.4x 28 and I traded them for 16.9 x 34 with cast hubs off of a Allis 6080. The 16.9 x 34 were brand new tires and the 18.4 x 28 side wall had cracks in them. The bigger tires sure makes it roll faster on the road and I have a 200 gallon milk cooler on 3 ph for gathering sap for maple syrup in the woods. Rolls a lot better in the bush over rough ground.

Now that I look it over, my last post sounded like a rant, sorry! 

Stu, I wasn't complaining by any means either.   I would just love to give the AC's justice at the pulls, and hopefully not have to cheat to get it done.   I think what Lonn was saying is a good way to go though too.   If you place in the money, you have to dyno to get it.   That way people also have the option of just not dynoing and giving away what they truly "have" under the hood.   No matter what you do, you're going to have some cheating going on, it's just the nature of the beast.   I'm just out to have fun.   It was good to meet you Stu and I will be there next year.   And if it's going to rain on Friday night next year, I think we should go to Fleet and spread some tarps over the track.   Give me a call, I'd be glad to help in the work.   You guys did alot of work to get things pullable on Sunday and should be commended for keeping it going.   Would have loved to stay later, but I was running out of clean clothes with my daughter pooping on me!!  LOL

If you look up on www.natpa.com they have the sizes. I beleive 14.9x28 is 170 sqin, 16.9x26 is 206 sqin. 16.9x28 is 209 sqin. , 13.6-38 is 168 sqin. 14.9-38 is 200 sqin., and 15.5-38 is 189 sqin.  I went to 15.5-38 to get a lever playing field and a shorter tire as comareded to a 14.9-38. It seems most of the domanite allis wd are 38".