Ok, here's my dilemma.

I have run a 14.0 x 32 for several years since we back halved the car. It is now a 4 link at 3200lbs. My question is whether or not there is something worthwhile to gain by stepping down on tire size. I rarely have tire spin but one wouldn't expect it with this much tire and this little power. Should I step down to perhaps a 29.5 or some kind of 10.5 combo? What do y'all think?

Current combo:
416SB
575hp, 540lbs tq
904 w/ 2.74 low gear
5:13 Dana
4 link at 3200lbs with me in it
Strange double adjustable shocks(rear)
8" 5500 converter
Launch at 4800, shift at 6500, traps at 6900
Current 60' = 1.39-1.40, ET = 10.49 at 123mph

The car would likely work better and run faster, with a 33x10.5 M/T tire.

Monte

if you went to a smaller tire you would have to take a lot of gear out of that thing. I am in the same boat with a large tire low hp deal. but I am not real worried about the ET loss if I can make it hook.

In regard to your question ,a young guy that hangs around my shop and helps me on my race car, built a 66 Dodge Dart 2dr Post Bracket car! This car weighs 3400 # w/him in car has a 416 S/b with a 800, d/p Edelbrock heads flat tappet cam, around 12.0 comp, and no spray! Trans is a 904 w/2.75 first and a 4.30 rear, w/11.5X28.5 Slick, using Cal-Tracs and their springs and shocks! This is an all steel except for a glass hood w/rear open scoop! I think thats about it for specs, the car turns steady times of 10.15-10.20 @ 131.00 mph in average midwest air! At Union Grove Wi. 60 FTs at1.37. It flat as hauls and there is nothing real trick in it. John Lang

I forgot to answer your question, yes your over tired! Why pull more weight than you need! Also the above Dart we don't know the HP cause it's never been on a dyno, the convertor is a Dynamic, No trans brake yet, he leaves on a 2 step at 2500, shifts (air) at 6500 clears lights at 7200! By the way that also is a cast crank! The convertor flashes at 4500! Later... John Lang

If you are just bracket racing then stay with the big tires. Do you care what ET it runs?????/

If you care or are trying to pick it up just for the heckuva it then I agree with Monte

I would think the car will be more consistent with the bigger tire; less tire may ET or MPH better but can make the car more track-sensitive.
My Duster's pretty similar, except 358" & approx 630HP, 5.38 gear, 13x31s, 5800 Dynamic, modified SS leafs, and seems sensitive to track prep. Might go to the Caltrac setup if I don't restore it to its original (period) SS/IA configuration.

All these answers make sense. This is also an old SS/IA car. I was pretty sure we would pickup ET with a smaller tire but since we run at lots of different tracks and lots of different weather conditions it seems to make sense to stay with the bigger tire for this protection. I really don't need to drop tenths off the ET because I like running at the top of Super Pro and knocking off 170mph dragsters all day. However, one always wants to know what the optimum configuration might be for any combo.

That 2dr post car is really kicking it for what it has in it. Way to go.

It may actually be MORE consistent with a smaller tire. Some lowered powered cars with big tires are not always consistent, because the car does not have the power to actually "work" the chassis to stick the big tire.

Monte

True to a point Monte - but he has a 4 link, he has and can put in the mechanical advantage of the proper IC and make the car "act" many different ways.

I have seen issues with over tires on LB cars and Spring cars. But to be honest - bracket racing = over tire, under power, loose converter and your winning rounds.

The truth is...on many days, when the weather cooperates, the car is dead on consistent. At our very last race we made 7 passes in a row within .007 and won the event. Obviously, there are days when we are not as "on" but it is usually a factor of DA or driver brain farts. As far as tire is concerned I don't think we could get more consistent. The car almost never reacts to air pressure adjustments. I have run between 9-13lbs without varying .01 on the 60'. I typically run the shocks at two clicks from full extension and midway on the rebound. No down track issues with this setting and the extension is mostly adjusted to control wheelstands. At this setting, on our first pass at the Thanksgiving event at Las Vegas the first launch was pretty exciting. I was able to watch an F-15 land at Nellis AFB between launch and the 1-2 shift.

I haven't really started to experiment with front shocks yet but that's kind of in the plan for this year. Still running non-adjustable worn out station wagon shocks.

Hello to all. I'm a new member, been following Moparts every day for about 2 months. I say keep the bigguns, enjoy the traction and knowlege that even if track prep isn't that good you'll be able to stick it! Good looking Duster; added it to my pic collection.

Welcome to Moparts.

Big tires don't guarantee traction. I ran 14" x 32" Goodyears
on a 340 powered 2830 lb. car and it took me awhile to get it
to hook. Big tires were no cure-all for poor track prep either.

I stand partially corrected. Big tires are no cure all. Laws of physics would state it's all about PSI to the pavement. I personally wouldn't spend $1000 for a couple mph, or a couple hundredths 60'.

Seems to me you are answering your own original post with your replies here.

Welcome to the jungle