Does anyone run 35" tires w/ 4.56 gears?

[Longshot270]

So jealous, that thing will be fun when you get everything adjusted correctly.

For tire size I'm gonna guess somewhere around 2770 as a start. Do you have a GPS? You can use it to dial in you speed perfectly by comparing the odometer readings.

[hampsterzone]

I have a GPS that works great. I only asked because you seemed to always have an answer. I usually mark the tire and drive until the mark has made one complete rotation. The measure the distance and I am usually very close. I was hoping that the Graphon will adjust for my gears and tires. Will it help the transmission shift better?

[Longshot270]

You can either measure that way (but use 3 or more rotations and get the average) but another way is you clear the odometer on both the GPS and your truck. Program your truck to a specific size and write that down (Very important step, you want to be 100% sure on the size you use). Drive at least 15 miles (the more miles the better) and divide the truck miles by the GPS miles. Then multiply that number by the tire size you programmed in.

[hampsterzone]

I see said the blind man! Makes sense to use an average. I will do that. I can't use my odometer because it will not read anymore. I posted about it but no one has replied. LOL anyways, thanks for everything.

[Longshot270]

Oh yeah, you replaced your dash. I dont know what to tell you on that one besides check your harnesses again. Might try the larger forums.

[hampsterzone]

Thanks, I do appreciate it. My odometer does not read out anymore as per my post. So that idea is out of the question. But the average suggestion makes every bit of sense. I will do that.

[Longshot270]

Years ago before GPSs and such, that is exactly what I would have done.

Here is the secret to reliable science. Always take multiple samples.

[Jackpine]

Bill SHOULD include your new Gear Ratio (GR) and Tire Size (TS) in your tunes. But, the TS is a bit of a WAG. Personally, I think you can refine the TS using a speed readout on the GPS and compare it with a speed readout on the Gryphon (not the dash speedo - which always reads faster due to mechanical errors).

If you stabilize the speed on the highway (70-75 mph is a good speed) and find a TS that gets them to match, you're golden. I've found my GPS speed stabilizes within less than 3 seconds at a constant speed.

Longshot, I'm going to "quibble" with your suggestion of 2770mm, it seems too large. A tire diameter of 35" has a circumference of 2793mm. Reducing that by 3% for squish give me 2709mm.

But, regardless - pick one of those values as a starting point. If your Gryphon speed indication is too fast, reduce the TS. Increase the TS if the Gryphon speed is too slow.

And, I'm sorry but I'm not coming up with any thoughts about your odometer.

- Jack

[hampsterzone]

Thanks!