just wondering what you guys with 285/65/18s and a gryphon are setting you speedo cal. number at?

When I first got the programmer and used the books formula I got a 2779 circum and when entered in it was about 10 mph off, when actually a 2400 is about the closest I could get to actual mphs

And yes the gearing is correct with what I have, 3.73s.

 

Unloaded circumference is 2600mm. Factoring in squish (4%), you should be at 2496mm (or so). When you enter the number, the Gryphon will round the number (up or down).

 

I believe I set mine at 2379 and I am dead on according to my gps. I am sure tire pressure will make a difference also.

 

what psi are you running? I'm at 55

 

Well, I'm on 285/60/18's at 38-40 psi, but have my Gryphon tires set to 2435. Which is less then 1 mph off compared to my GPS. Hopefully that'll help you zero in on yours.

 

To be honest I dont know. I had them put on about a month ago and never checked how much they put in them. Its not my daily driver so it just sets at the house all alone. Im such a bad owner.

 

That's what I get also and I posted it for him over at PHP's forum.
LOL's

 

I know, I was just seeing what others are running