IDK what power level you're at with that set-up, but I had a factory 03 Mercury Marauder that I installed an under hood roots Eaton/Magnacharger supercharger in, with an intercooler. I also installed headers, an aftermarket torque converter that yielded a 3,000 rpm stall speed, and 4.56 gears in the rear. I tipped the scales at the dragstrip@4,444 lbs with my 205 lbs of body weight behind the wheel and the half tank of 93 octane pump gas that I always ran both on the street and at the track with.

Without me in it, the curb weight was close to 4,200 lbs so the car was fairly close to being the same weight as what you're running. I had the car for three years, and I ran NITTO 555R drag radials on the street and at the drag strip, and I kept them@24 psi on the street, and@17psi on the drag strip and 17 psi worked the best for me with that car. I ran 12.0 to 12.2 second ET's, (depending on the air temperature) and consistent 1.6 second 60 foot times with that heavy tank of a car that it was, and on pump gas alone.

I had factory stock suspension both front and back, and I didn't even disconnect the front anti-sway bar, which usually is a no-no for drag racing. But I never had any wheel spin issues with those tires@17 psi. Of course driving on the street, I went through two pairs of them every summer, but that's the cost of better traction. Yes, I could still do burnouts with those tires from merely a dead punch from a standstill position in first gear, but when I wanted to get traction, I just walked it out of the hole from a traffic light in first gear, and I could then hit full throttle as soon as it hit second gear, and still avoid wheel spin. With the standard street radials, I couldn't even do that. You probably already know this, but I would highly recommend that you drive like an old granny with those tires whenever it rains. It wouldn't take much to hydroplane with them, especially when there are puddles. I always did a good pre-race burnout with them too.

What I also learned about the drag radials is that due to their soft compound rubber, they're much more sensitive to temperature changes than the harder compound rubber of standard street radial tires. On the street they provided the most traction when the air temperatures were above 60 degrees, but as soon as the air temps dropped below 50 degrees, I'd begin to notice a loss of traction during hard throttle inputs, and when the temps got into the upper 30's at night time, those drag radials would spin in first gear even with less than half throttle inputs, ( especially around turns). Almost like the street was wet, even when it was completely dry.

They're really good tires for street and strip use. You just have to know their limitations on the street. Also due to their soft compound, I never got more than 8,000 miles on a set of them. Based on what you said, my guess is that if you're making well below 600 HP under the hood, ( my heavyweight car made 475 HP) and you can't get the heavy weight vehicle you have to hook consistently at the track with the NITTO drag radials@17 psi, then your front and rear suspension needs work, and/or isn't set up correctly.

Do you have a front swaybar? And if so, do you unhook it when you're drag racing? What else do you have for FRONT suspension?

 

If Nitto has a 295/65/15 tire available (30") and you have space, the taller, slightly wider tire should help enough from what you describe.

 

x2 tire height matters

 

Thanks for your insights! I should have given you more info, especially my restrictions due to my 40 year old build. Front suspension kits were not available back then and did not want the straight axle set up. Grafting clips was pretty common back then, that being said the front suspension as is gives me 1 3/4" of travel before hitting the bumpers. No easy way to change this without major modifications. I have disconnected the front sway bar but did not make any difference as I think the lack of travel is the main issue (very loose front shock). As far as power goes, about 230 at rear wheels, best truck has run is 14.98 (which amazes me for what it is), foot braking and leave at 1700, governor in tranny shifts at 3800, go through top end at 3800. The 'rv' torque producing cam pretty much gives up at that point plus I have the D3VE heads with stock cast manifolds which information I have seen they don't flow after 4000. I have been experimenting with tire pressure/burnouts with some luck but I can't seem to be able to trust the truck will hook. I can probably get a 295 in so that maybe an option to try. Nitto told me 22 lbs, no burnout, just clean off the tire which I tried and worked at times but again not consistent. Lately have been doing more of a burnout, running them at 18 psi which seems a bit better but still not working later in the day. I have had a few times 'tire chatter', not sure if that's the correct term but after some looking the consensus seems to be too low pressure or too much heat in the tire? Rear has stock 7 leaf springs, 3 clamps forward, 50/50 Gabriel shock. I have seen many say the drag radials are very temp/pressure sensitive. Would you suggest taking the pressure down later in the day to maybe 17 or lower? Sorry, I know this is an odd ball and nothing someone would build to race, just trying for some fun and go a few rounds. Thanks,

 

...... foot braking and leave at 1700,

That^^^ right there just might be your biggest problem. Soooo many guys do that^^^^....they load up the converter with the two foot method and some guys do get away with doing that, but I will tell you that when I tried launching my car that way, it ALWAYS spun the tires off the line with the NITTO drag radials. I solved that problem by simply leaving the starting line from a 750 rpm idle. That's it. And I ran consistent 1.6 second short times regardless of the time of day, and regardless of the air temps, and I did that at two different drag strips at a whopping 4,444 lb race weight, with merely 475 HP under the hood, ( flywheel HP).

Here's the problem with loading up the converter like that BEFORE the car begins to leave the line: You're causing your pinion gear to climb up along the ring gear, and loading your rear suspension BEFORE the launch begins. So in essence, you're removing the suspension from the equation, and it cannot work for you during the launch, since you're activating it BEFORE the launch.

I'm sure you're well aware of how the rear end haunches up like a cat ready to pounce on a rodent, whenever you load up the converter with the gas pedal. That is less than ideal to put it mildly. Like I said, some guys get lucky and with their particular vehicle combination, they get away with launching the car that way. But a number of cars just won't launch consistently by doing that. Try leaving the line from an idle, and just stomp on the loud pedal when you get the bottom amber light. There's a very good chance that will solve your problem.

Now of course you already know that having such a short front suspension travel isn't helping, but I'll also say that it might not be any big deal with a 14 second vehicle. LMK how things work out when/if you try launching off an idle rpm. Oh and BTW, I never recommend taking any drag radials lower than 17 psi. Now radial slicks are likely a whole other story. But I don't believe there's any benefit in running drag radials@15 psi or lower. If they aren't hooking for you@17 psi, then something else besides the tires is wrong. That's assuming that your drag radials aren't too old and dry rotted, or just too worn and have seen their better days.

 

Yankee Chevy, thank you for your replies. Will definitely give that a try as in the old days when I was racing was always with stick cars so do not confess to know much about autos. My logic was, which could be wrong for sure, stock Ford converter advertised at 1750 stall, Detroit true trac needs loading to force the spiral gears to engage and finally by starting at a lower rpm and 'flashing' the converter my thought was it would hit the tires harder? Tires are new, maybe 1000 miles so far but I must say are great in the rain (I am in Hawaii and so far, I have never driven to the track or home without being rained on), still drive like a granny but without loading the true trac behaves like an open re and I think that helps. We race next weekend if the weather cooperates so will try your advice. Yes, oddball combination with problems related to racing but it actually runs pretty consistent if it doesn't spin. Thanks again.

 

I'm having similar problems with NITTO 325/75r15s RIIs.
Car runs 11.89@113 but 60fts are soggy with 3.33 gears and 3,800lbs.
1.71 is best 60ft but it's just blows the tires off 60% of the time.
Leaf springs, Rancho shocks,440 automatic.
I leave about 2,100.
Never tried off idle but think it 🤔 would be tough to cut a good light.
As slow as the 60fts are i didn't anticipate traction issues...

 

Never tried off idle...

You really SHOULD. If your torque converter is working correctly, and is set up correctly with the required stall speed RPM for your specific vehicle combination, then the the torque converter will do the work, and there's no need to load it up while the car is sitting there at the starting line. Doing that defeats the purpose of your suspension geometry as well as your torque converter.

 

One way I'd hook a DR that wasn't getting hooking up when flashing the converter, I'd foot brake it and just roll into the gas a bit slow and not stab it.

I went 1.59 on 18" Nitto NT05Rs in a 3800 lb 5th gen. With that car, I later had some 275-60/R15 555Rs I never ran them at the track but I could tell they were gonna hook about the same as M&Hs for me, I would have had to foot brake and roll into the gas , maybe go low 1.6 60 foot. I did go 1.47 in this car on a 28x17 Hoosier slick.

 

This tire looks great on a 12" wheel.

That's what width wheel I use. What I found was if mounted on a 10" wheel the tire wears at the middle. On a 12" it wears pretty evenly.

Of course, as you guys probably know, it depends on the tire size. With the P295's, P305's, and the P395's, sure you'll need at least a 12" wheel width. But for P255's, and probably even for P275's, a 10" wheel width is fine.

 

I drove on 555Rs for about 5 years, all over, in heavy rain, no issues.

 

I drove my street/strip DAILY DRIVER/work commute car for 3 years and 54,000+ miles using the NITTO 555R's and I never had any accidents nor serious issues either. But of course I wasn't as aggressive with the gas pedal in the rain with them, as I might be with standard street radial tires, and there's just no way that anyone can say that the drag radial tires are gonna wick away the water as well as standard radial tires do. Especially on highways which tend to collect puddles in certain places when it rains. it's just common sense.

 

Yeah I think rolling into the gas I could have gone upper .5s on them, that's what I did on the street.

Makes for a fun daily

 

Sorry for the late reply, went to the track to test advice from here last Sunday. First pass while goo was fresh no spin and left at off idle rpm. My reaction time took a bit of a hit but 60' was only off .02 so not bad. Sat for 3 hours waiting for a second pass to really check on my traction problem, but it never came. Packed up and went home. Will try again next month and let you guys know how it goes.