My tires are a strange mix...are they ok?

[Roadster Guy]

I have had my Vette over two and a half years and logged 6000 miles. When I bought it there were new tires on it and the car was very mint with very low mileage, so I did not really pay much attention to the tires. I have never had any problems with the car but this winter in storage I really checked out the tires and here's the scoop:

Passenger side I have Goodyear EMT Eagle GSC. The rotation direction is correct and the correct side is facing out. On the driver side I have Goodyear GSC but not runflats. Rotation direction is correct, but both rear and front have the Insides facing out! All the tires are the exact correct stock sizes as per the black book and wear is minimal and seems even. The car handles well and is smooth at all speeds and even when I have touched 100 mph on the highway I can take my hands off the wheel and things appear fine (maybe a slight drift to the right).

I guess there are two issues...runflats on one side, regulars on the other....and correct mounting on one side, insides facing out on the other. So what do you guys think? Weather is improving fast and I hope to be out cruising soon!

 

[c4cruiser]

IIRC, the Goodyear GS-C tires that were introduced on the 92 Vette and kept for subsequent years, were not only directional, but asymmetrical. There was a left-side tire and a right-side tire.

I got rid of my GS-C's after they were on the car for about 8 years. The compounds in the tire dried out and the tires just didn't have any traction. Very noisy and would squeal on even shallow turns.

I guess if you do mostly street driving, there should not be any real issues except that you could get a flat on the GS-C non-runflat side and have to mount the spare. You didn't say whether or not the car had the LTPWS optin or not; that could explain why two of the tires are EMT's.

I'm not really a fan of these tires any more simply because there are a lot of tires available that are much grippier, have much longer tread life and much cheaper. The GS-C is no longer made so when they wear out, you will be searching for a different model of tire.

 

[WhalePirot]

Normally tires should match left to right, in pairs. As your car is not pulling and seems to drive well, I don't see a reason to worry, aside from what was mentioned.

 

[Roadster Guy]

Thanks for the insight C4 and the confirmation WhalePirot. Yeah, I have the spare tire, so I am ok for now with the non runflats and my driving is street. I also find the tires loud and easy to squeal. I follow the tire discussions on this site closely and save interesting suggestions and comments, so I will use that info when tire shopping time arrives.

I just wanted to make sure the runflat and non runflap mix and the left/right issue were not a safety issue and from what you say it isn't. Looking at the tire tread design I suspect the left-right placement may partially have had something to do with water displacement when driving in the rain....something I don't do unless caught in it briefly.
RG

 

[froggy47]

I have run "flipped" tires to even the wear (in edge vs out edge) due to autox. So long as the rain grooves are not backwards there is no problem with this.


As to run flats vs regular you would have a problem under extreme performance demands, but for crusing you're ok.

Previous owner diden't want to pay the premium for runflats.

 

[Roadster Guy]

Thanks froggy....good to know and now I am good to go.

I guess the rotation would have to be facing the wrong way for the rain grooves to be backwards. I am suspiciours the previous owner got a deal on the last of the gs-c runflats and non runflats in stock and bought them all placing them on the car in the best possible configuration.:ugh
RG

 

[Hib Halverson]

The two Gooyears, the Eagle GS-C and the GS-C EMT are vastly different designs. One has a much stiffer casing designed to have EMT properties. The two tires will handle a bit differently and have much different levels of road noise.

The reason GS-Cs are directional is the water-channelling of the tread grooves when the tire is on wet surfaces. The reason the tire is assymetrical is the outside area of the tread is different than the inside to enhance traction in cornering.

A car with std. GS-Cs on one side and EMTs on the other will have some unusual handling quirks when driven hard. This is because the std. GS-C has a more compliant casing which is better for tire performance at the limit. The EMTs, because of the stiff casing, don't work as well near the car's handling limits. In easy driving, you will notice a higher level of road noise on the side you have the EMTs.

The reason you have the tires on the left with the insides facing out is the previous owner put right side tires on the left...either though a mistake or, perhaps, a purchase of used tires at a low price to get the car sold.

Was this car originally equipped with GS-C EMTs?

 

[Roadster Guy]

Hib, according to the copy of the GM window sticker in front of me it shows no charge for the ZR 17 S/B Radial B/W Tires and the car came with a spare tire and jack and the spare tire delete option is not indicated....therefore I assume it was NOT equipped with the GS-C EMT's when new. My build sheet copy is at home not here in my office so I can't check it right now and maybe that is not indicated on it anyway.
I agree with your assumption that the left side tires were a mistake or purchased to sell the car...probably the latter. Since I became aware of the tires I have pondered the safety issue and handling. The increased noise from the EMT's is there and explains why one hears more road noise on the passenger side.....I had thought that was more a design quirk of the car.

Anyway, I guess I have four choices.....use the tires until they need replacing or put left side matching runflats on the left side or move the left side tires to the right where they belong and buy two non run flat tires to matchfor the left side or buy four new tires.

As the tires have some wear on them now, adding two new ones will mean one side of the car will always have tires being replaced before the other which I don't like the idea of. Also as C4cruiser mentioned earlier....the GS-C's are an old tire model and there are newer and better choices out there.
I am leaning towards using them until they are a little more worn and then using the information discussed previously on this site about tires to buy a proper set of four non run flats that are mounted correctly.

I enjoy your articles Hib and respect your knowledge and opinion. Money being no object I suppose everyone would chuck the relarivley new tires on it now and put four new ones. What do you think about this situation? You do mention the handling quirks when driven hard....can I safely use these tires for a couple of months while taking my time to find the tires I want at a decent price bearing in mind not to push the driving limits? I love the car and especially the LT4 in it.
RG

 

[Tuna]

I'll second Hib here. The EMT and standard tires should not be mixed on a car.
I'd look at a new set of GoodYear F1 D3's for your LT4.

BTW, you might want to check the RPO list sticker under the rear compartment lid and see just what you are supposed to have as for as options go. The runflat option is WY5. Runflats should also have the Low Tire Pressure Warning System also (how else are you going to know you have a near flat tire?). That's RPO UJ6.

 

[WhalePirot]

It sounds like you won't have a big issue here, unless you drive close to the edge. I am not one to waste rubber or anything else, so if it were my decision, I'd retain the proper tire rotational direction and swap two tires, leaving front and rear as L/R pairs. That assumes that the tires have similar wear. When it's time for tires, it's time to match everything up.

Hib's command of facts is simply awesome, isn't it? Truly, a valued resource!
TRIVIA?: Radials can acquire a 'set' in the belts from the direction they rotated. Early in the radial days, some shops recommended (before non-directional tires) rotating tires in an 'X' or modified 'X' pattern, while others recommended front to rear; same side. Sometimes a car would start to pull to one side or the other, due to the belt 'set', with the 'X'ing.

Retaining the directionality of each tire is why Froggy must remount each tire to even the wear. Some very high performance tires, however, have rubber with different compounds, hence differing hardness, on the outer vs the inner areas of the tire. Grooves (tread) can be similarly varied.

 

[Roadster Guy]

I have to agree with you Tuna and Hib that run flats and non runflats do not mix. I was thinking about it last night and each year I seem to drive a little more robustly so tires become a factor. I guess if you are just putting around it is not an issue as mentioned earlier.

Funny enough, I was pondering what WhalePirot was saying and thinking of just checking around first to see if I could replace one side to match up exactly with the other and therefore have 4 matching tires (leaning towards 4 non run flats for better ride and noise) and then get 4 new ones when the time comes. I agree WhalePirot that waste is not a good thing.....by the way a nice bit of tire trivia too.

Oh yeah Tuna, I am going to check the RPO list sticker in the back compartment when I get home tonight to see what's what with the tires and low pressure gauge options...thanks for the heads up on this.

Getting warmer day by day....just waiting for some hard rain this week to wash away all that salt on the roads and then afterwards instead of surfing the net for tires I'm just going do a little slacking off at work and cruise around to the various tire shops and sort this out........
RG

 

[Rich96c4ce]

Because you have a 96CE, it would have come with LTPWS and EMT tires, and a jack. That is standard equipment on a CE. You should have had 4 different tires on the car.

 

[Roadster Guy]

Because you have a 96CE, it would have come with LTPWS and EMT tires, and a jack. That is standard equipment on a CE. You should have had 4 different tires on the car.

Thanks for the info. I did not know that this was standard equipment on the CE....interesting. All the bases are covered then if one goes with a new set of EMT's or a new set of regular tires....
RG

 

[Roadster Guy]

You may be wrong on this one Rich96c4ce.....

Because you have a 96CE, it would have come with LTPWS and EMT tires, and a jack. That is standard equipment on a CE. You should have had 4 different tires on the car.

As I had never heard about the CE fact that all Collector Editions came with EMT's and LTPWS, I decided to browse through my Corvette Black Book. Result: there were 5412 Collector Editions produced. Yet, only 4945 of the WY5 option (EMT's). Therefore, it seems to me, not all CE's could have possible had this option. And my RPO sticker shows neither option WY5 or UJ6. Looking through my Corvette Specs book also I see no mention regarding the EMT's and the low tire pressure warning system being part of the CE package.

I just wanted to try and sort this out so that this thread's information is somewhat correct. If you have a source where it says the CE had these two options as standard equip then let me know.

Anyway, thanks for your input. Hope I don't sound like Magnum P.I.
RG

 

[Tuna]

I did the same - checked the black book and a few other books - I can not find any place that says the LTPWS and EMTs are part of the CE package. So, I don't believe they are. I'm looking at Corvette Specs 84-96 by Mike Antonick and it does not list the run-flat or LTPWS option as part of the Z15 package.

If you do not have the RPO codes for LTPWS and the EMTs then they did not come with the CE.

My ex-CE was a Z51 car so it obviously did not come with runflats and it didn't have the LTPWS which it could have had.

Since your car does not have the LTPWS installed, it should not have run-flats installed. GoodYear 'requires' tire pressure sensors for run-flat installation. Without that, there is no warranty.

 

[Roadster Guy]

Sorry bud...but your warranty is toast!

Tuna, thanks for the confirmation.....Hey did not think about that....no LTPWS then no Goodyear warranty on run flats. Good point.
RG