RPM on Geostar 11 R 24.5

[luvrbus]

Helping a friend on his speedometer do any of you guys know the RPM on this tire 2 days and I come up nothing except they are made in China thanks for any help


good luck

[robertglines1]

came up with 43.5  OD  6610lb@110psi. on steer.looking farther.could compare to know tire chart using the OD as referance 136.6 inch rollout per revolution 464 rev per mile..someone should ck my math.

[Dreamscape]

came up with 43.5  OD  6610lb@110psi. on steer.looking farther.could compare to know tire chart using the OD as referance 136.6 inch rollout per revolution 464 rev per mile..someone should ck my math.

Where did you find that? I'm like Clifford, came up with nothing.

Paul

[robertglines1]

my home page is my yahoo..just typed in search for tire specks for the brand and size...geostar 11r-24.5 specifications    Bob

[akroyaleagle]

Thanks for the info Bob! I too came up with nothing.

Paul does this change the dip switch settings?

[white-eagle]

so does this discussion mean my 2 mph error on my speedo is due to differences in tire specs?  i just check my rpms, my speedo and my gps.  i believe the gps.  and it shows my mph is about 1.5 mph high at 65mph.  at 70 on the speedo, it shows about 68 on the gps.

do i really need to adjust the speedo?

[Dreamscape]

Joe, I'm going to recalculate and get back to you.

Paul

[Dreamscape]

Try this Joe,

1 - off
2 - on
3 - off
4 - off
5 - on
6 - on
7 - on
8 - off
9 - off
10 - on
11 - on
12 - off

The only ones that change from before are 2 and 3, all others stayed the same. I just posted all of them for reference.

Paul

[TomC]

Using the diameter of the tire times 3.1416 to calculate the circumference of the tire is incorrect.  You'll always be around 10-15rpm off.  A tire squishes down and that is called the rolling radius of the tire.  So a 11R-24.5 actually spins at around 474rpm, not 464rpm. That difference at 75 can be the difference between your speedo saying 75mph or 73.5mph.  Good Luck, TomC

[luvrbus]

Thanks guys we were using 480 rpm for the tires 480 should have him with in a mile or so thanks again now go back and calculate again Paul


good luck

[Dreamscape]

1 - on
2 - off

All the rest stay the same.

That should get him somewhere between 1 and 2 miles +-! (fingers crossed)

I hope he sees this, otherwise all bets are off!

[akroyaleagle]

Thanks everybody! You guys are Great. It's pouring rain here today but I will post the results when I get them.