HPP III Question
10-01-2002, 09:45 PM
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HPP III Question I have recently installed 3.73 gears. I have an HPP 3 and am changing the gear ratio, When i do that though, it is asking me to put in the tire height. I have no clue what the height is. It gives me a range of anywhere from 24" to 30". The rear tires I have are Nitto Drags 275/40/17 . Anyone know what I am supposed to put here? TIA.
10-01-2002, 10:52 PM
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Re: HPP III Question Uuuuuuhhhhhhhhmmmmmmmmm... Measure 'em! DOH! <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />
Seriously, just take a tape measure and measure from the pavement to the top of the tire - then that is what you enter into the HPP3. Good luck!
Seriously, just take a tape measure and measure from the pavement to the top of the tire - then that is what you enter into the HPP3. Good luck!
10-02-2002, 05:58 PM
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Re: HPP III Question The HPP3 manual says:
Place a chalk mark on the tire where it contacts the pavement and also mark the pavement. These marks should be at the center of the tire footprint pointing straight down to the pavement.
Roll the vehicle in a straight line until the chalk mark makes one revolution and is pointing straight down at the pavement again. Mark the pavement again at this new spot.
Measure (in inches) the distance between the two (2) marks on the pavement. Divide the measurement by 3.14159. This will give you the tire height in inches.
I used masking tape and drew a line with a marker. My 275 g-Forces' d was 25.0" (C/pi = (78 11/16")/3.14159) & not 25.7" as per specs. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Place a chalk mark on the tire where it contacts the pavement and also mark the pavement. These marks should be at the center of the tire footprint pointing straight down to the pavement.
Roll the vehicle in a straight line until the chalk mark makes one revolution and is pointing straight down at the pavement again. Mark the pavement again at this new spot.
Measure (in inches) the distance between the two (2) marks on the pavement. Divide the measurement by 3.14159. This will give you the tire height in inches.
I used masking tape and drew a line with a marker. My 275 g-Forces' d was 25.0" (C/pi = (78 11/16")/3.14159) & not 25.7" as per specs. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
10-04-2002, 10:58 AM
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Re: HPP III Question Another method: Stand tire on level floor. Place a 24" level across very top of tire. Measure from bottom of level to floor. The 275 Nittos should measure 25 3/4 to 26", depending how much air you're running.... WJ. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
10-04-2002, 03:31 PM
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Re: HPP III Question Enter your tire info into this website is it will breakdown all the measurements for you. http://www.csgnetwork.com/tireinfo4calc.html
10-04-2002, 03:33 PM
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10-05-2002, 08:22 AM
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Re: HPP III Question Dlatwood, the U.S And Metric Tire Size Information Calculator that you listed is neat! For a 275/40 17" tire it gives a circumference of 80.62" and a diameter of 25.66".
However, my SLP option, BFGoodrich g-Force 275/40ZR 17" tires, by using HPP3's method detailed previously, gives a circumference of 78.69" and a diameter of 25.05"! I trust what I see and the HPP3 way is accurate . . . the speedo must continually reflect the actual distance travelled, divided by the time, if it is to be accurate . . . computers do a good job, but only if the numbers that they crunch are real. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
However, my SLP option, BFGoodrich g-Force 275/40ZR 17" tires, by using HPP3's method detailed previously, gives a circumference of 78.69" and a diameter of 25.05"! I trust what I see and the HPP3 way is accurate . . . the speedo must continually reflect the actual distance travelled, divided by the time, if it is to be accurate . . . computers do a good job, but only if the numbers that they crunch are real. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />