Need more traction

[coldrider]

So I swapped engines and now the truck wont hook at all. While it’s been fun roasting tires at will, its time for a change. Here’s what I’m working with

67 SWB
M122 supercharger (caddy STS-V), 7-8psi
6.0 LS2 (9.5:1 comp)
Terminator X Max
4L80E, Yank SC Series 3000 stall
3.73, True Trac
295/40/20 Nitto 555 G2 (29.3" tall) on 10" wide wheels

The thing is... besides the traction issue, I really enjoy the truck the way it is so am not looking for major modifications right now (tubs, new suspension, etc) so am starting with the obvious upgrade of tires and was looking at these

Mickey Thompson ET Street S/S:
305/35/20s (28.4 tall x 12 wide)
305/45/20s (30.8 tall x 12 wide)
MT Tech Support says either of these are fine on a 10” wide wheel.

and

M&H Drag Radials:
275/40/20s (28.7 tall x 10.8 wide). 10” wheel ok
305/35/20s (28.4 tall x 12 wide). 11” wheel required so these are out

Seems like the MT 305/45s are the obvious choice, but what do you think? Any other options I should look at? Do you think I’m wasting my time trying to keep the 20 x 10s?

Lots of experience here, so appreciate any/all feedback on traction upgrades that don't require going full-race mode

[D.B]

Originally Posted by coldrider

So I swapped engines and now the truck wont hook at all. While it’s been fun roasting tires at will, its time for a change. Here’s what I’m working with

67 SWB
M122 supercharger (caddy STS-V), 7-8psi
6.0 LS2 (9.5:1 comp)
Terminator X Max
4L80E, Yank SC Series 3000 stall
3.73, True Trac
295/40/20 Nitto 555 G2 (29.3" tall) on 10" wide wheels

The thing is... besides the traction issue, I really enjoy the truck the way it is so am not looking for major modifications right now (tubs, new suspension, etc) so am starting with the obvious upgrade of tires and was looking at these

Mickey Thompson ET Street S/S:
305/35/20s (28.4 tall x 12 wide)
305/45/20s (30.8 tall x 12 wide)
MT Tech Support says either of these are fine on a 10” wide wheel.

and

M&H Drag Radials:
275/40/20s (28.7 tall x 10.8 wide). 10” wheel ok
305/35/20s (28.4 tall x 12 wide). 11” wheel required so these are out

Seems like the MT 305/45s are the obvious choice, but what do you think? Any other options I should look at? Do you think I’m wasting my time trying to keep the 20 x 10s?

Lots of experience here, so appreciate any/all feedback on traction upgrades that don't require going full-race mode

My thought is tooo much low end torque for a truck that has no weight in the rear. I know a larger diameter exhaust helps reduce low end torque some. Taller tires, lower gears such as 3.08's and/or different stall converter.

[litebulblsc]

More sidwall does help. Some racing groups limit width on 15" rims but allow wider with 17"+. (Drag radials specifically)

Is this a trailing arm truck?

[coldrider]

Originally Posted by D.B

My thought is tooo much low end torque for a truck that has no weight in the rear. I know a larger diameter exhaust helps reduce low end torque some. Taller tires, lower gears such as 3.08's and/or different stall converter.

DB - I agree a taller tire would help which is why I was considering the 305/45 but this one apparently doesn't have near the demand. Been looking a little more and it seems like its out of stock (ie special order?) for a few months at the likes of Jegs/Summit. And I want to at least try a stickier tire before making big changes to gears or the converter, so the 305/35s are looking more and more likely as they're in stock just about everywhere I look.

Originally Posted by litebulblsc

More sidwall does help. Some racing groups limit width on 15" rims but allow wider with 17"+. (Drag radials specifically)

Is this a trailing arm truck?

Lite - I hear ya on sidewall, but that's the tradeoff.. the look I want vs the performance I want and when I got the wheels, the crate 350 I had was pretty anemic and didn't need any help from the sidewall. I didn't know about the diameter to width ratio you're describing, thanks for sharing.

And yes, I'm on trailing arms.

---

I will say that I was little surprised that even though both are 305s, the tread width difference between tires was more than I was expecting. I suppose this is where some folks could debate contact patch area and whether a taller but slightly narrower tire is worse or better off than a shorter but slightly wider tire. I don't have enough experience to say one way or the other, only that I dont really feel like waiting weeks or months, so the short/wides are probably going to get my $.

[litebulblsc]

If you look at your table, the "short and wide" were measured on a wider wheel. That is most likely the difference in the measured tread width

[coldrider]

ah, good point, i missed that

[mongocanfly]

I'm lost when it comes to tuning...it voodoo to me, but could a tuner do some adjustments to the tune and help on the lower end?...it's seems now every racer with fi is adj on them for max performance
Sweet lookin truck btw..!!!

[PGSigns]

For more traction here what may help. Raise the front of the trailing arms and shim the pinion back to about a 1/2 degree down. This will raise the instant center and ad bite to the initial hit. Get the tire from your chart with the most side wall. Reduce the tire pressure to let the side walls work. Get a set of double adjustable shocks. Work with the settings to allow a harder hit with the extension setting. That allows the shock to extend easier on the hit and that will help drive tire down. then tune the compression to control the rotation to help keep it hooked. The drag radials are not designed to hook on a slick surface. Radial prep will rip your shoes off. Radial cars dead hook the tire.
Jimmy

[coldrider]

Originally Posted by mongocanfly

I'm lost when it comes to tuning...it voodoo to me, but could a tuner do some adjustments to the tune and help on the lower end?...it's seems now every racer with fi is adj on them for max performance
Sweet lookin truck btw..!!!

Its a little bit voodoo to me, too, which is why I hired the tuning out, at least for now. I'm trying to learn but not brave enough tweak anything without a second set of eyes on it. I suppose I could talk to my guy about making some adjustments, but not 'til I swap tires. And thanks for the kind words on the truck!

Originally Posted by PGSigns

For more traction here what may help. Raise the front of the trailing arms and shim the pinion back to about a 1/2 degree down. This will raise the instant center and ad bite to the initial hit. Get the tire from your chart with the most side wall. Reduce the tire pressure to let the side walls work. Get a set of double adjustable shocks. Work with the settings to allow a harder hit with the extension setting. That allows the shock to extend easier on the hit and that will help drive tire down. then tune the compression to control the rotation to help keep it hooked. The drag radials are not designed to hook on a slick surface. Radial prep will rip your shoes off. Radial cars dead hook the tire.
Jimmy

Thanks for the tips. I've read a couple threads here about flipping the trailing arm brackets after lowering to improve traction. In your opinion is this a must-do, noticeable improvement or is it one of those "every little bit helps" kind of things, cause I glance under there occasionally and then say "not today"

Already failed on point #2 and got the tire with the lesser sidewall, mostly cause I didn't want to wait weeks or months. 305/35s ET SS's on the way, be here tomorrow. And I'm not quite following your comments on drag radials, except that you might be implying I'd have been better off not buying them. All I can hope for is they hook better than the super-hard G2s that are on there now.

I'll read up on the adjustable shocks cause just running cheapo KYBs right now. If there's a good product or info page you wanna share, please pass it along. And thanks again