Thinking about getting a dyno tune, but I'm running Q rated BFG A/T's. Will this be a problem? I can always bring along my stockers and bolt them up at the shop, but then the tune would be done with a different effective final drive ratio, if that makes a difference.

What do you think?

 

keep the a/t's on if that's what you're wanting to run with on the street/track.
btw, where you getting your truck dyno'd? gforce?

I gotta get my truck and the sandrail dyno'd in a couple weeks at gforce.

 

leave them on... it will be more accurate

 

I was going to drive out to Nelson's in San Antonio. I wasn't sure how fast they need to spin the rear wheels to get the full tune (redline in third, I presume?), and if that would exceed the speed rating on the big ol' knobby BFG's.

I will have 4.10's by the time I do this, so I guess I need to figure out what mph I will be running at redline in third.

 

You won't need to take it all the way to redline, but until power drops off. I don't know the diameter of your tires, but my truck with stock tires went about 110 mph during my dyno run. Bigger tires will have to run faster. Oh, and I have 4.10's.

If you changed to smaller tires, you would have a higher HP and TQ than with the tires you have on. You should leave the tires on that you plan to run to get accurate numbers.

Mike

 

I found an RPM calculator, and 106 mph (R speed rating, not Q as stated above) in 3rd (1:1 ratio) the engine would only be turning about 4500 rpm. This is assuming that the converter is locked, which at WOT, I'm guessing is not the case. What rpm does a stock-ish truck top out at?

If this ends up being problematic, I might just go with a mail order tune. If I really up the HP down the road, I'll just sell the lift and put some ZR rubber on it!

 

i left my BFG A/T 315/75r16 's on when i went to the dyno.....but my numbers wernt even close to where they should be cause they did a SHITTY i mean SHITTY tune on my truck!! im sure if you put more air in the tire your numbers will come out higher!!

 

My truck 03 silverado SS with 305/50/20 BFG KDW, 4:10 rear. I go to about 150MPH in 3rd gear and the tires distort. The stockers were down right dangerous looking. They even started to shake at 150MPH when I let off. Kind of like the funny cars when they launch and sometimes get the shakes. Scared me enough to stop doing 3rd gear pulls with the stockers.

Just make sure you have equal pressure in each tire. HAVE FUN!

 

Yikes, and I still have almost two more inches of sidewall than you too. Definitely won't be pulling up to 150. I'm pretty sure that I'd run into problems with the driveshaft long before that anyway.

I'll proably just trust the dyno operator, and if he says it's a no go, I'll let discretion be the better part of valor.

I would have figured that the SS's came with at least V rated rubber stock.

 

i have taken my truck wit the lift kit and tires to 115 mph on he street ....still felt great!!!