NSW Corvettes

Technical Tips => Brakes, Suspensions, Steering, Wheels & Tyres => Topic started by: Vettech on May 08, 2019, 02:50:40 PM

Title: 1990 C4 Tyres
Post by: Vettech on May 08, 2019, 02:50:40 PM
Any one out there like to recomend tyres for a 90 C4 Coupe.

Running Std 12 slot OEM polished alloy wheels 9.5" x 17" all round.

Currently 275's on front (not too bad Pirelli's)  but has 315's GY Eagles on rear whilst tread depth is legal, tyres are very very hard, cracking, and chunks missing.
Went OK to QLd for nationals, but the rain made for very liverly handling.

Time for new ones, but I will go down to the OEM 275's, since 275's seem also to be easier to get.
There are Nitto and Kumho, treads on these look OK, but I wonder about road noise at highway speeds.

Any recommendations gladley recieved.
Regards


jk
Title: Re: 1990 C4 Tyres
Post by: MY081 on May 08, 2019, 04:35:25 PM
Joys Merc had Continentals we put Pirellis on and it transformed the car and very quiet . If you wish to go that route I may be able to get a good price for you > Ray
Title: Re: 1990 C4 Tyres
Post by: Bfit on May 08, 2019, 06:41:04 PM
I would seriously consider rubber , preferably round  in a size that’s suitable for the size of the rims you have.
Bfit
Title: Re: 1990 C4 Tyres
Post by: MY081 on May 08, 2019, 09:44:02 PM
Bfit do you have a preference on colour !!!!!!!
Title: Re: 1990 C4 Tyres
Post by: Bfit on May 09, 2019, 07:21:27 AM
Mmmm dark very dark possibly black, with iridescent Daytona yellow embossing.
Bfit
Title: Re: 1990 C4 Tyres
Post by: Vettech on May 15, 2019, 03:24:11 PM
Been reading up, appears tyre rules world wide changed ~2000.

Tyres prior to 2000 can/maybe have a made date moulded into the side wall, but were hard to decipher.

From 2000 there is a string of codes ie "DOT XYZ ABC" then an oval cartouch with four numbers in it eg "4303"

This exact same number is on my front Pirreli's and indicates "43rd week of 2003" manufacture.
So the fronts are 15 years old - and here I was thinking they were not tooooo old.

The rears look really old, worn, cracking and  have no code I can see, so me thinks they are ~19 years old.

Thanks MY081, the mustang had Pirrelis, as of today has four new ones - thru some deal she got thru work, but still dear.
Pirrelli's seem ok wet or dry but soft - she got 62,000 kms. (Manufacture date "0519" on these new ones).

Once upon a time you bought tyres and stored them to allow full cureing of the rubber, now a days they contain some rubber,
plastic, fabric, steel wires, polymids, silicon rocks, and only god knows what else, as a result it is now better to use them as fresh as possibl since they become hardened, ďevelope flat spots etc etc...

Tomorrow I'll sus out the shocks, they are bilstrin so are possibly OEM items, so could be up to 28yrs old.
.
Title: Re: 1990 C4 Tyres
Post by: MY081 on May 15, 2019, 07:28:48 PM
Yes uncle Doug the Pirreli's are soft (just what you need ) 62000 on the Mustang that sounds pretty  good to me 37000 on Joy's car. Ray
Title: Re: 1990 C4 Tyres
Post by: Vettech on May 17, 2019, 03:24:46 PM
Yeah the tyre fitter said it was good and shows the service people were doing the right thing.

Anyway on yesterdays Codgers run with 9 other Vettes, I spoke to Tim who runs Kumho's, said wet& dry ok, quite on the Hwy.

I think the chunky block tread Kumho is way to go, as someone said "if they fill the bill and are cheap - then get them, since you will never wear a set out".

Even though my fronts are Pirrelli, good tread, they are ~15yrs old. So maybe a full set all round 275/40ZR17's.

The shocks are Bilstein no sorry Bilstein/Delco, made in "WESTERN" Germany -the wall fell in ~89ish and East & West joined in 90.
Products were from then on stamped  "made in Germany" or just plain "germany" ' DDR, GDR, East and West went out the door.

Removed RHF Wheel, cant get the shockies top nut off without destroying it, but got it far enough to turn it for the date, umm its pre 2000.
Also it can be easily pushed in, it does come back slowly.

So - a set of shockies are in order, when all this is done I might invite Bfit out for a weekend run from Kangaroo Valley over the back pass and into Berry, and then we will see how good his C6 goes.......this time.

Title: Re: 1990 C4 Tyres
Post by: Lefty on May 19, 2019, 05:43:47 AM
Hi,
Would you get bilsteins again, or go with konis, or other?
Best

Lefty
Title: Re: 1990 C4 Tyres
Post by: Bfit on May 19, 2019, 05:51:36 AM
Hi,
Would you get bilsteins again, or go with konis, or other?
Best

Lefty

Good question
Title: Re: 1990 C4 Tyres
Post by: MY081 on May 19, 2019, 12:09:31 PM
A very good Question !! I've had both' in my opinoin the Konis were better on the front and Bilsteins better on the Rear . Not sure of the type of Bilsteins I have but there the Yellow with Blue top ( double acting or something ) There fantastic and really hold the rear end down . Ray
Title: Re: 1990 C4 Tyres
Post by: Vettech on May 19, 2019, 08:34:20 PM
Funny but all three of my Vetts have had original Bilsteins on them, but all were a trillion years old.
Ergo - I have no real appreciation of what a good Bilstein does.

I put KYB ON THE 87. AND whalla, felt like a new car.

I may only have this car for..... a short time, so I definitely wont wear either tyres or shocks out.

The Kumho's with a set of Gabriel Ultra Gas are cost effective - so time to bite the bullit.

I'll get D4 to order them on the hairnet asap, since trying to get a look at the RHF shock, unfortunately now means I cant retighten that shock.

HERE'S A QUESTION - some shocks have an allen keyed top, others like bilstein have a reduced dia bolt with two flats, Is there a special tool ?

Probably quicker to cut them off, the back are bolts so should come straight off.

Regards.
Title: Re: 1990 C4 Tyres
Post by: Bfit on May 19, 2019, 09:04:58 PM
Bloody hel you have enough vette’s to start your own club
Bfit
Title: Re: 1990 C4 Tyres
Post by: Lefty on May 20, 2019, 01:21:09 AM
Thanks for the responses
I have seen KYB under $200 a shock
Konis a bit more around1200 a set of 4
Bilsteins for my other car cost 2 k
Very harsh ride but great feedback and good at speed
Too firm at low speed and slippery in the rear
Any one got some other comments?
Best
Lefty
Title: Re: 1990 C4 Tyres
Post by: Bfit on May 20, 2019, 10:58:40 AM
I have a set of KYB shocks I purchased for a C3 , I neve  mounted them as I changed directions on that set up.
I believe they are a good option for C3's
Bfit
Title: Re: 1990 C4 Tyres
Post by: Bfit on May 21, 2019, 06:29:51 PM
 Cecil hills corvette & muscle car club has a reasonable ring to it .
Bfit
Title: Re: 1990 C4 Tyres
Post by: Vettech on May 25, 2019, 06:55:57 PM
Well the shocks arrived Friday, I've now fitted both rears.
Close inspection of tyres clearly shows they are past their use by date, so to the old Bilsteins.

Will do the front when able, also I now have a light on the dash "change oil".

OMG these cars are fun.
Regards.
Title: Re: 1990 C4 Tyres
Post by: Vettech on May 26, 2019, 05:06:27 PM
Well all four fitted, the rears had lots of oil under the plastic top cover.

Now when you  put the peddle down, it lites up both, no more fishtailing.

Now - next month some tyres, while on the topic my fronts although ~14 yrs old still look good and are Pirrelli's.

Just put a set of Pirrellis on the Mustang, maybe worth considering.

Oh! and yes Bfit, I had to cut the FRH shocky off, and to answer my own question, the socket style shocky top bolt holder is available, but I saved the twenty bucks and used the disk cutter... job done.










Jh.
Title: Re: 1990 C4 Tyres
Post by: Lefty on May 29, 2019, 07:31:36 AM
If the old bilsteins are rebuild able, is there a small market for these to be sold on?
Best

Lefty
Title: Re: 1990 C4 Tyres
Post by: Vettech on May 29, 2019, 08:06:08 PM
Good question.

I know the electronicly adjustable bilsteins on the LT1 are rebuildable at an astronomical cost when freight to the US is added.