Boosted_01 R

Hey guys was testing my cousins car on the weekend, and was having the problem with the slicks below 15psi. At 15psi the rear of the car starts moving around on the top. Its not wheel spin 100%. At 18 psi and above the car is stable and doesn't move around on the top end.

The only thing i can come up with is; mounting a 8 inch slick on a on a 7 inch rim. would this problem go way with a 8 inch rim? The car is a Datsun 260Z, SR20 powered, 405WHP. it runs on 24.5x8x15 M/T Slicks

Am guessing its the rim size because on my type R i have the same size slicks on 6 inch rims(USDM ITR wheels), and i notice on the bumpy return line, its moves from side to side with the steering wheel straight.

Any input would be great, thanks

jnv255

U can run up to 2in over..
I have 15x8 rims with 26-10 slicks

SlicksMH

Put bias ply front tires on, and problem solved.

SlicksMH

Boosted_01 R

The front tires are Toyo R888

mike93eh2

get an alignment. that fixed it for me.

SlicksMH

Is it a radial ? Do not mix a radial front with a bias ply rear.

SlicksMH

Drag_S14

I agree with SlicksMH. Get a bias ply front runner and you should be fine. Slicks will tend to sway a bit at speed, and when compounded with a stiff radial front runner, can aggravate the situation. A bias-ply front runner will sway with the rear and you will hardly notice it if at all. I ran 26 x 8.5 with a radial front and noticed a lot of sway at only 80-90mph. I've run over 140 with bias-plys and haven't noticed a thing.

0Innes

iTrader: (3)

yep, i know quite a few cars that swapped ends at the top of the drag with a Bias Ply on the back of the car and a regular street tire up front

Boosted_01 R

What brand front tires/rim set-up do you have on the car (links would be great if possible)

BTW thanks for the input guys

Drag_S14

The 26x8.5 was my old S13. On my S14, I've got 27x10 Hoosier Quick Time Pro's in the rear, with Mickey Thompson ET Front 26x4.5. http://www.summitracing.com/parts/MTT-3007/

HTH

ExVtec

Good gawd thats scary.

Boosted_01 R

Thanks again for the reply................ That's a serious tire in the back, what kind of power you making?

Thanks

SlicksMH

You do not know how many times I have seen this combo, and racers get into trouble.

Be SAFE and GOOD LUCK Boosted_01 R

SlicksMH

Boosted_01 R

They should have a warning about this stuff, when buying slicks for a RWD car. On my Type R the tires are fine.

But yeah, safety come first in a sport like this. wont run under 18psi in the slicks till we get front tires.

BTW with no burnout, its pulled a 1.76..........60' LOL at 18psi in the tires

SlicksMH

I here you, you have to talk to the right people to get the right answers.

Be SAFE.

SlicksMH

ExVtec

So whats the difference between a radial ply tire and a bias ply tire?

Would someone care to give an example of doe's & don't?

SlicksMH

Hello ExVtec,

A bias ply nylon cord likes to roll and a radial stainless steel belt likes to cut, so you are moving the steering wheel back and forth. It will feel like you have a flat tire in the rear, and it's not a good feeling so you will have to back off the throttle.

Be SAFE.

SlicksMH

ExVtec

I see. Your typical street tire is a radial w/belts...so slicks are normally bias ply then, thus the rolling?

So as you are doing mach 2 down the strip, you will get some roll on the top end, and by having bias ply's on the front AND back the front/rear roll in sync and is less noticeable vs bias in the rear and radial in the front which would cause you to over-react and swap ends.

That basically sum it up?

SlicksMH

Yes sir.

Have a Good Day.

SlicksMH

Dark_Teg

The back of my Mustang walks side to side a little at the top of fourth but i just got used to it.

SlicksMH

It only takes one time.

SlicksMH

Dark_Teg

I run the slicks @8psi I have ran MT ET drag slicks and Hoosier drag slicks and I always figured it felt that way cause of the low tire pressure.

Drag_S14

At 29psi the car did 465whp on a DynoDynamics through the powerglide with a little wheel spin. It's on 45psi now, but it spun worse on the dyno so no idea. I'd guess around 600-650 on the DD. I've also got a 100shot direct port and a 50 shot single

SlicksMH

If you can find a friend that has a set of bias ply fronts, put them on the car. Your world will change.

SlicksMH

Boosted_01 R

That's pretty sick. 9's am thinking