[Jackpine]

Originally Posted by robandkat

Thanks for the info Corey. I think my tire size hurts the performance.

I also used 2689mm for 305/65/18 bfg at/ko tires that are 33.7 inches. This should correct the speedometer right?

After I get the custom tunes, if I change tires sizes, can I just change it in the tuner or do I have to get my tunes redone for the new tire size.

With my CAI and the canned tow tune it seems to drone alot (sounds like a vibration in the CAI) will the custom tunes help with that. I didn't notice it as much in the canned 91 tune. Sorry for so many questions this is all new to me.

Hey! Another guy who includes his Wife, Sweetheart, whatever in his screenname! Good on you buddy!

Bill will be able to reduce or eliminate the drone your CAI is causing. The fact that you are getting a drone with the tow tune though is evidence that the canned tune is doing "something". I could immediately tell the difference between my canned tow tune and stock when I first got the programmer. Primarily, I found downshifts were happening much more quickly and were completing quickly. There was none of that, "I wonder if this thing is ever going to speed up?" when I was trying to pass someone. I also noted an increase in gas mileage.

The custom tune seemed to refine it even more and I got a further increase in gas mileage.

But, these are heavy trucks and a tune is not going to make them into top fuel dragsters.

The Tire Size (TS) you entered does not account for "squish" - the flattening of the footprint that actually reduces the rolling radius. I've found that if you reduce the unloaded circumference by about 3%, your speedometer and odometer will be much more accurate. In your case, try subtracting 81mm from the circumference and entering 2608mm. When Bill writes your custom tunes he will use a "squished" value for the tires you say you have.

If your stock tires were 275/65R18 (like mine) and your Gear Ratio (GR) is 3.73, the effect of mounting the larger tires was like reducing your GR to 3.55. You'd need to install 3.90 gears to get your old "zip" back.

BEFORE you change the TS (and GR) in your Custom Options menu, please take the time to read the Q & A I posted on this here: http://dygytalworld.ehost-services13...ead.php?t=1101 (It's in the FAQ section of the Gryphon forum). Custom Options are an easily misunderstood process, so please make sure you know what you're doing.

Finally, welcome to the forum!

- Jack