Please help - tire change + things got worse

[Maroon 6.2L SS]

Hi all. For my B-Day the wife said it was O.K if I bought M.T E.T Street SS Drag Radials to replace my current Nitto NT555R Drag Radials (as long as I sold the Nittos) I was excited about this but things turned out bad.

My avg 60' with the Nittos was 1.94
My avg E.T with the Nittos was 12.88

Today was my "first points race" and I had the new M.T E.T Street SS Drag Radials on.

My avg 60' with the M.T was 2.02
My avg E.T with the M.T was 13.14

I'm very confused. How did my 60' and E.T go down with the M.T tires when they're supposed to hook better??? The weather wasn't much different, temp within 10 degrees of before as well as pressure and humidity and same drag strip etc...My burnout was the same and I've always left at the same rpm. Tire pressure was 18psi

I did see that the M.Ts were a hair taller than the Nittos. But still same size 275/40/20.

Please help!!!

[Bo White]

What stall? Are you spinning?
Buddy of mine gets low 1.9 with stock converter on regular street tires

[Maroon 6.2L SS]

Stock converter, no footbraking, idle launch. Same thing I did with Nittos. It didn’t feel like I spun.

[Chris49066SS]

The computer starts pulling timing if your engine gets too hot, which can happen while sitting and waiting to get out to the line, or if you're making repeated back to back passes. Theres head winds, bad gas, how exactly you're hitting the accelerator, too low PSI in the tires, etc, all kinds of variables really. If not spinning, I'd consider trying a higher pressure.

[frankwjr]

those new sticky tires either need a little more psi or you need to hit it with a higher launch rpm...the ultimate is to have the tire spin 1 or 2 revolutions allowing the rpms to build quickly before they completely hookup...I and my old clutch found out the hard way that you can have too much tire...


I have a line on some 'vette 17's wrapped in M/T bias ply...sold my Nitto 05r's on 18's over the weekend...THAT way like banging yer freakin head against a brick wall...


good luck!


peace

[QUICRNU]

Did the Nittos spin? I doubt they did at an average 1.9x 60ft

If you are launching off Idle, and the Nittos didn't spin... Then stickier tires wont make you faster if you are launching at the same off idle.

The differences in those times is easily accounted for with any 1 of countless variables from day to day, as mentioned above.

Brake stalling to find the max rpm you can launch at with minimal slip is the best way to have compared the two tires, even though track prep weather etc will effect it from day to day too

[Maroon 6.2L SS]

Thanks for all the great info everybody. I will now apply what I've learned from you guys tomorrow at test/tune. Love this forum.

1. I realized that I didn't have these new M.T Drag radials broke in yet according to what I read on the website. I definitely broke them in yesterday on a misty day. Lit em up hard into third gear. The compounds came to the surface and there was a distinct line left on the tire and they were now super sticky.

2. I'm gonna try 24psi in them vs 18psi to start. I ran better on street tires at 25psi than I did on these at 18 psi. Plus I'm only running 450 reg. hp with stock 3.27 gears in an auto with no aftermarket stall converter.

3. Instead of launching at 600rpm idle, I'm gonna launch at 1000-1500rpms while on the brake. I practiced in the parking lot at work.

I will post my results when I get home from the strip. Thanks again for all the info everybody!!!!!!!!!!!

[Joe M 2012 2SS]

What mods do you have to get to 450 hp?
Stock our cars are around 320 rwhp.
After basic bolt-on's you'll get about 50 more (cold air, LT's, UDP, PTB).

I had the Nitto 555R/20" and had similar 60' times as you when I just had these basic bolt-on's.

I didn't need to upgrade tires until I added a CD 3200 TC, I went with MT ET street R in 18" instead of 20".

If you were going to get different tires, I would have got 17" or 18" wheels. I wouldn't expect you would see a difference, by swapping to different 20" tires.


I have since added nitrous and several rear end mods (gear, true-trac, DSS axles, TL's/TA's), and my car cuts a 1.4X 60', but has less than 500 rwhp.

If you have 450 rwhp……. I don't see how a 20" tire would ever hook if your launching hard.

[Chris49066SS]

Originally Posted by Maroon 6.2L SS

2. I'm gonna try 24psi in them vs 18psi to start. I ran better on street tires at 25psi than I did on these at 18 psi. Plus I'm only running 450 reg. hp with stock 3.27 gears in an auto with no aftermarket stall converter

450 reg. hp still isn't bad at all with just a couple bolt ons!

[Maroon 6.2L SS]

Joe M, not 450 rwhp, 450hp (at the crank/motor?) estimated with most basic bolt on and suspension parts

[QUICRNU]

Originally Posted by Maroon 6.2L SS

Joe M, not 450 rwhp, 450hp (at the crank/motor?) estimated with most basic bolt on and suspension parts

You should be able to pound those MT SS off the line as hard as the stock stall will let you at that power level.

While you may not really get the full benefit of them now, they are a perfect upgrade to support putting future mods to the ground. Assuming you don't wear them out first, you did a good thing.

Yes 17s are better....but MT SS on 20" is still better than 555r, as stated you may just not notice that difference until converter and power are added.

[zz430camaro]

MT is slightly larger diameter by .18", does not seem like much but with a tire that tall (almost 29") it could be hurting a little. See if you can borrow some 26" tall tires from someone and try them out, or even 27" to 28"

[Maroon 6.2L SS]

Hey all. Just got home from the strip (after making changes) and had improved results but was still a little bummed, but it is what it is.

My best tire psi was 25-28psi warm (adding psi "definitely helped")
My 60' improved to an avg of 1.973
My E.T improved to an avg of 12.948

Bottom line, properly "breaking in" my new M.T E.T Street SSs before going to the track helped, going up in PSI helped. I tried footbraking with a 1500rpm launch and it was a trainwreck for me. If I could perfect it I'm sure it would also improve my 60' and E.T a little more. For now I'll just stick with my 600rpm idle launch.

I also realized that switching to the M.Ts vs the Nittos didn't do much for me as far as performance (probably due to only having basic bolts-ons, 3.27 gears and no stall converter) but I did notice that my consistency seemed to improve. That's good!!!

Thanks to all of you helping me with advice and tips and opinions. Now it's time to focus on my R.T etc...I will be selling the Nittos soon if anyone is interested. I'll post it on the selling forum. They have maybe 15 runs on them with light/mod burnouts.

Thanks again everyone!!!

[zz430camaro]

so why was the 1500 rpm a train wreck?