Hey guys new to this stuff and Iam trying to do just a basic tune for a 05 4.8 crew cab 4l60e I drive daily . I was trying to use the BC tool but I am obviously doing something wrong because when I put in my tire size of 31.9 275 55 20 it?s asking to shift WOT wayyy high . Any help would be greatly appreciated.
Just realized the photo didn?t upload working on trying to get it to post
But it’s asking 1-2 54mph and 2-3 102mph 100% throttle
Last edited by SOTO; 01-13-2023 at 09:04 AM.
Did you add your current gear ratio in as well? If you left the "final" line alone with the 3.23 gear ratio, the numbers you posted are what the calculator puts out.
02 Tahoe, Rebuilt 5.3, PRC 2.5 heads, BTR Stg2 V2 cam, 50lb Injectors, Speed Engineering LT's, Offroad Y, Magnaflow catback, Built 4L60, NP241 swap etc etc...
You have to do the gear/tire wizard in the "edit" tab first. Then enter the info into BC trans. The tool works great when you get used to it.
Tune and Datalog along with gear ratio and such would be helpful.
The blue cat tool is very nice but you have to put the right info in to get the right info out.
Thanks for the reply guys . Yes the truck has a 3.23 gear in it with 20 inch Denali take offs . And yes I matched everything up in the tire wizard first on Hp tuners . Just seems like I’d be bouncing off redline WAYY before I ever saw 102 mph
Yup I sure did truck does have a 3.23 gear .
I did just seems real real high mph
In the most polite possible way I can. Please tell me you didn't put the rim size in for the tire change wizard. As in 20" tallOriginally Posted by SOTO
Lol no , I put in 31.91 for total tire size since it’s a 275 55 20 . With a 3.23 gear
Cool. As a side note, never go off of what a tire says on the sidewall. Always measure with a tape measure. Almost all off road style tires are off by at least 1" and sometimes as much as 2.5".
If you wanna get really technical about it, there's a difference between the measurement from the ground to the top of the tire, and the actual number being used, the length of the lever, from axle c/l to the ground x 2.
use r1x2 not d.jpg
As an example, my tires claim 28.6" dia. Measured from the ground to top of the tire is 27.5". But axle to ground x 2 is 26.4".
Last edited by blindsquirrel; 01-13-2023 at 02:11 PM.
I guess before anything I’ll TRY making the changes but … factory it’s wanting 73 mph shift and even if I take 2 inches off the tire on the bc table .. it’s still going to want almost 100mph in 2nd gear … thats what I am having a hard time believing lol
3.23 gear with those tires is just plain dumb.
https://www.dennysdriveshaft.com/pot...alculator.html
5600 RPM, 3.23, 31.91" is...
1st/3.06 53.8 MPH
2nd/1.63 101 MPH
3rd/1.00 164.7 MPH
A reasonable gear for that tire size, 4.11, gives reasonable WOT shift speeds of 42, 79, 129, and a just about perfect 2000 RPM cruise speed in 4th of 66 MPH.
Ya luckily I don’t tow with it just daily commute. Come late spring I might head out to the junk yards to look for a sierra Denali rear end or v max truck .
Make sure the speedo calibration in the tune matches with bluecat. Dont forget to set your shift lead time in bluecat, usually for a 60e i use 1 or 1.25.
You should use 31.1 for that tire size.
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