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May 22, 2010 | 07:24 PM

#31

jake08

Elder User

Joined: Jun 2007

Posts: 807

Likes: 0

From: Cypress,Ca.

Quote:

Originally Posted by jake08

Hi all; I have a 223ci. with Ford O Matic. I just switched from 3.73 to 3.31, 29in tall tires. I advanced the timing a couple degrees, the truck runs great! I have NO lugging with local driving. It should be about 2500 rpm at 65mph. Going to be on the freeway tomorrow, will report back. The little 223 is stronger than you might think.

Hi all; just reporting back after putting 60 freeway miles on the truck. I drove no faster than 2500 rpm, and it drove like a dream. Happy to also report that she got a trophy for best stock truck. Some very nice folks in Chino Hills. Have a great nite, I sure will.

May 22, 2010 | 07:51 PM

#32

Bill W

Hotshot

Joined: Jan 2007

Posts: 11,564

Likes: 4

From: Tucson

Congratulations! how many is this now 50, 100....

May 22, 2010 | 10:52 PM

#33

jake08

Elder User

Joined: Jun 2007

Posts: 807

Likes: 0

From: Cypress,Ca.

Hi Bill; Thanks for the thought. A whole lot less than that. See you at the Western Nationals. We have a great show on tap this year!

May 22, 2010 | 11:41 PM

#34

HT32BSX115

Logistics Pro

Joined: Feb 2005

Posts: 3,952

Likes: 117

From: Upper Left Coast

Quote:

And we've had this discussion before. First, the tire isn't round with weight sitting on it - it's an oval. So you won't get an accurate diameter measurement (within an inch) on it. And the error is multiplied by 3.14 when you mathematize it. It's a significant error.

You quoted what I said.....

Quote:

Originally Posted by HT32BSX115

True if you just use the diameter of the tire.....

But measuring the "rolling" radius (center of the axle-to-ground.....and then "doing the math") is virtually the same as measuring the "roll-out" circumference.

I thought I said that when I said you have to measure the ROLLING RADIUS (which DOES account for weight on the tire.....um, it's the same thing as measuring the rolling circumference....there's no additional error when multiplying by a constant either)

And I also agree that it's probably easier for some to just put a tape measure next to the tire and mark it with piece of chalk.......