Paging KenC (Tire Expert) - tire advice needed -

[Pascalz28]

My tires are almost bald and i dont have enough $
for drag radial. I might be able to get a new set
of tires before i go to the track but its a bit f a squeeze.

Is it okay to run bald tires at the track?
I would think that bald (or almost bald)
tires are better for drag racing at
the strip in dry conditions as tread was made for rain so
you dont hydroplane. Is it true that a bald tire would
grip better?

I'm getting new tires soon and Im wondering if I should
get them put on before or after I go to the track.

Also whats the lowest psi I should go with on street
tires? 28....26... Lower psi means more surface area
in touch with the ground but it also mean sidewall
flex, increased wear, and increased rolling resistance.

the front tires i'll take up to the rated max 44psi.

thanks for any insight you could give,
Agent P
98 m6, cut out, mccord power plate, k&n, lid

[Injuneer]

Not Ken, but some things to think about...

Lowering pressure slightly may increase the contact patch area, but if you go too low, the center of the tread will cup in and you will lose contact patch area. You have to experiment and see what pressure gives you the most consistant black pattern on the pavement.

There is nothing wrong with "sidewall flex" when you are drag racing.. that allows the tread surface to deform and increase contact patch.

The problem with a worn out, treadless tire is that tires can have a tread compound that is different than the main body of the tire. The tread is compounded to grip, the outer casing of the tire may be a harder material, and traction will be poor. Shallow tread will grip better, if you are still in the softer compoound, but treadless casings will probably not hook at all.

If "bald" means there is metal or nylon fabric showing, do not drive on them at all.

Personally, I'd wait until I could put good tires under it to go to the track. A blowout at 100mph isn't going to be a pretty sight. I've seen street tires with good tread fishtail at the end of the track and put people into spins.

[Craig 2000 TA]

One more quick point... every track I have been to does some sort of tech inspection. Even the laziest of tech inspectors has always looked at my tires. There is a darn good chance that even if you decide not to heed Fred's advice they will not let you race.

The cheapest tire I have found is the Kuhmo Ectsa Supra 712 series. 83 bucks a tire on tire rack and its rated a W I think for 164 mph which is obviously over kill well for most of us anyway

[Pascalz28]

re

My Rear tires are below the legal "2/32 of an inch" limit but not
completly bald (no tread showing). You can still see a bit
of tread left.

The front tires however are right at the 2/32 inch limit.

Under the above conditions do you think they'll still not
let me drag?

thanx for the response guys,
P

[wolfdogs]

fred's correct........

some companies do use a soft undertread compound though.. but it wears very rapidly and that could lead to a blow out.

id get the new tires.
.. now...as far a pressure.. that depends on the brand designation of the tire... tire like the gforce kd's have extremely stiff sidewalls.. so you could run 22-24 psi in the rear...where as other brands..might require at least 26......or even 29-30 to keep from cupping the center crown. what kind are you going to get?

[Pascalz28]

re

right now I have Michelin Pilot XGT z4
set at 34 (all 4) psi (for daily driving)

Im still not sure which tires im going to get
for I must wait at least another 2 weeks before
i have enough to buy them anyways.

but i'm considering: (from www.tirerack.com)
Pirelli P7000 SUPERSPORT Z rated 96$
Kumho ECSTA 711 (High Performance Summer) 56$ H rated

H rated goes up to 130mph, my traps wont be more than 110mph
so i figure i'll do fine with H rated tires, is that true?

are the compounds in H, Z rated tires different enough to
realisticly affect my 60'?

thanks,
Pascal z28

[wolfdogs]

Re: re

Originally posted by Pascalz28
right now I have Michelin Pilot XGT z4
set at 34 (all 4) psi (for daily driving)

Im still not sure which tires im going to get
for I must wait at least another 2 weeks before
i have enough to buy them anyways.

but i'm considering: (from www.tirerack.com)
Pirelli P7000 SUPERSPORT Z rated 96$
Kumho ECSTA 711 (High Performance Summer) 56$ H rated

H rated goes up to 130mph, my traps wont be more than 110mph
so i figure i'll do fine with H rated tires, is that true?

are the compounds in H, Z rated tires different enough to
realisticly affect my 60'?

thanks,
Pascal z28

may i be blunt? good.

Kumho's suck. go to slp and page git_sum about his experience 3 weeks ago with them......on his firehawk.

dont run 34psi....... thats too much pressure. run 32 front and 30 rear. the door jam sticker from the o.e. tells you 30/30....for a good reason. extensive testing went into those pressure for the best contact patch, best wear, and the proper functioning of the tires cord body/belt design, crown edge wedge, the whole nine yards........ 20,000 dollar for each vehicle model! i did further testing and found that using 32psi up front gives you 4k more miles on the crown edge wear with the same handling and contact patch.