Houston area (along with DB's not from Houston) BS thread

Red, i think you might be a little high on that correction factor. where'd you pull that from?

 

Guess im not getting 14mpg? Lol

 

depends on your actual tire size. my 35s actually measure as a spot on 35, and my correction factor is in the 12.5% range.

 

The 35 gives you a 14.6% larger circumference, but that equates to a 12.7% drop on your revolutions per mile.

 

I guess the best bet would be to actually measure the tire height ?

 

bingo, gotta use the the factor asociated with distance, not size.

that's the best way to do it. tire size calculator will get you a good ballpark, but you need to measure to get the true value, since sizes vary so much

 

Think we measured last time, came out to 34

 

Which would be the circumference, the actual distance that is being traveled per rev. Correct me if I'm wrong, but If you're trying to manipulate the mileage driven (distance); would you not want to use the percentage associated with the increase in distance. The revolutions aren't a distance measurement, although they happen to be indirectly based off of distance.

My math a while back led me to use the circumference difference... Of course I'm no mathemetician

 

It would make more sense (to me anyway) to use the circumference of the new tire and get a measurement of the old tire and get the difference in % to be more accuraate than diameter no?

 

Sounds like yall know what yall are talking about to me

 

Clicked on thread to see the bad ass 25 mpg toy on 40's.
Are you guys saying you don't need to correct the miles driven after regearing? You're definitely need to correct after regear, your tranny only knows it's own rpm, and your miles are based on stock gears at tranny rpms, if you change your gears, your tranny still thinks you have stock gears. You need to correct for gear ratio and tire size.

 

fixed.

 

revs per mile and circumfrence are directly asociated, and therfore use the same factor. while you can derive the factor from diameter, it takes more steps, and isn't directly equal. remember pi*r^2 from back in highschool

for manual transmissions, you are correct, you need to correct for gearing changes. that is because the computer get's it's infor from the transmission itself. with automatics on the other hand, the computer get's that infor from the wheelspeed swensors (downstream of the diffs), and therfore, will only be thrown off by a tire size change. you could regear your tranny, transfer case, and diffs, and still have an acurate dash reading on stock tires.

 

Lol, that works too.
I didn't realize the speed sensors were after the differential. Thanks

 

Well maybe I miss spoke with that. It depends which direction you're going with the factor though... Talking about Circumference you're going from a smaller to larger number. You will get a higher percentage difference (14.6 increase). In reference to revs/mile you're going from a larger number to a smaller number. The percentage will be smaller (12.7 decrease) and it will be subtracting from the original versus adding to.

I figure you'd want to keep the proper percentage changes with the same units... 14.6 distance increase if you're manipulating the distance driven. I don't see why you'd use the 12.7% rev decrease to increase the distance value.

 

this thread is way too fucking smart today.

 

Got back from lunch to find the outlets in my office are dead. I guess it's time to go home.

 

Next time I see you I'll bring a few ounces of that flocculant. The possibilities are endless.

Those are the best pages.

I'll work on this during my lunch break.

 

http://houston.craigslist.org/cto/4229312605.html