Speed rating?

[osdmike]

Hi!
I like the old Trans Am look, with 15" wheels.
But it´s hard to find a 15" quality tire that is safe, for high speed.

I´ve found this tire for the rear:
295/50 R15 108V Ventus ST RH 06


http://www.ityre.com/en/tyres/catalo...ok/size/17233/


But I can´t find a tire for the front.


Now I have 265/50/15.
25,63 dia. 10,51 section width.
The size is perfect,but they are
S-rated = 170-180km/per hour.


I had GoodYear Blue Streak for a while.
They didn´t last very long on the street.


Any suggestions?

---

[BAD68GTO]

S=112 MPH
T=118
H=130
V=up to 149
Z=149+

The worst tire made today is better than the best crap made 30 years ago and I have been close to 200 MPH on the street. I would not worry too much unless the sustainable speed will be for over 20 minutes straight, and I LOVE high speed and why I normally drive over 150 MPH weekly, raced at Pocono Raceway and LOVE racing.

[osdmike]

I have a vibration problem at 80, and it gets worse the faster I go.
I have checked the pinion angle, and the driveshaft is new.(came with the Keisler Tremec kit)
So I thought, maybe the rear tires could cause the problem.
No vibrations in the front/steering wheel.

.

[Yoda4561]

I've hit 120+ when I had a 72 Olds Cutlass on s-rated BFG Radial TA's. It was actually smoother at 120 than it was at 50. Get the tires balance checked first, then look elsewhere. I've heard of some instances where an out of round drum brake caused issues at speed.

[John Wright]

I have a vibration problem at 80, and it gets worse the faster I go.
I have checked the pinion angle, and the driveshaft is new.(came with the Keisler Tremec kit)

Try taking the driveshaft loose at the pinion yoke U-joint and turn it 180° and bolt it back up. Worth a try, doesn't cost you anything but a few minutes of your time, and sometimes it works.

[BAD68GTO]

Try taking the driveshaft loose at the pinion yoke U-joint and turn it 180° and bolt it back up. Worth a try, doesn't cost you anything but a few minutes of your time, and sometimes it works.

This is a terrific idea actually, but I would check the rim/tire balance first and observe if the wheel is bent while it is being balanced and no more than a few ounces of weight on the wheel, over that, rotate the tire on the rim and rebalance.

[osdmike]

Thanks Guys!
I´ll check tomorrow.

[BAD68GTO]

Mike you might want to also look at your front harmonic balancer to see if it did not back off, your trans flexplate did not start to back off (had this happen to me and it started slowly and then good bad over time) and lastly bushings in the rear, but that is WAY at the bottom of the list, rims and tires first.

[osdmike]

I checked the tires and had them rebalanced.
I looked at the rim in the balancing machine and I couldn´t see it move up and down,or sideways.
The tire moved up and down a little,though.

When I put the car on jackstands, with engine running ,and let the wheels spin,the rim on left side moved slightly up and down.
Could it be the rearend axle?
It´s a Mark Williams 31 spline axle.
I´ve had no accidents with the axle. (4000 miles on it since new)


When driving the car, vibrations start at 75mph. and gets worse the faster I go.
When I disengage the clutch and put in neutral, let the engine idle at that speed, I still have vibrations.

Driveshaft or rearend axle?,........or?


----------------------------

[Yoda4561]

Maybe one of the tires is no good, the rim movement on one axle sounds a bit odd though, might want to look into that further. Switch rims on that axle and see if it follows the wheel or stays in that one spot, could just be engine torque/driveline vibration showing up.

[osdmike]

With car on jackstands and wheels removed,motor spinning(5th gear) ,I still had vibrations when speedometer showed 80mph or more.
So the wheels seem ok.

Also tried to turn U-joint 180*.Still vibrations.

I used a dial indicator to check brake discs,and if the rearend axles were moving up/down.They did ,but not much.
Checked the driveshaft with dial indicator and I noticed it wasn´t straight.

So I put a hose clamp on the driveshaft and tightened it.
Used it as an adjustable weight.
Started the engine and took it up to 80mph.
MUCH BETTER !!
Also tried to go 120mph. ALSO OK !
So the new Driveshaft caused the vibrations!
So, balance DS ,next!

Thanks for Your input,Guys!


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[opnwide]

Glad you got that figured out, Mike. Mickey T makes the only speed rated 15" tire I know of (sportsman S/R). Rated H or 130mph.
They have a 26X12 for the rear which should work well with their 26X10 front.