OK. I've exhausted the great debate about which tires to replace my OEM tires on my 2004 Coupe.

Through the process someone mentioned the reason my fronts are rounding/cupping on the outer edges is because it needs an alignment. I kinda ignored this because when I drive the car it doesn't pull to the right our left and drives very straight and it only has 15,000 miles on it. But it's getting worse so I'm thinking there is in fact something wrong even though I can't feel it.

Today I was looking through more posts and I saw some comments about that said when you get new tires you need to get all four wheels aligned?

They actually meant to say all four tires balanced right and the front end aligned right? Is there something perhaps I don't know?

This is my first vette and I'm working off convential knowledge about alignments and balancing.

Thanks

 

They meant balanced.

When you put new tires on, you have to have the wheels balance so that it doesn't vibrate as you head down the road.

Alignments are also important - that is what is putting your suspension where it needs to be so you do not wear the tires too quickly. There are three angles that are dealt with, camber, toe and caster (which is non-wearing). Just because the car travels straight doesn't mean everything is set up right!

If the tire is truely cupped it can also be indicative of a bad shock.

 

With an independent rear suspension you can adjust the rear tires/wheels also I believe?

 

C5s generally wear the front inside edges down IF you do a lot of highway driving, if you do a lot of curves, they wear even. This is due to the factory specs, which increase handling and feel.

 

I find it a little hard to believe that the shocks on an '04 with 15K miles are worn out or failed, though it is possible.

I tend to believe that the issue is alignment. With an IRS car - a four wheel alignment is critical.

The balancing issue is also critical - I would strongly recommend that you have a Road Force balance performed once you purchase your new tires and have them mounted. I would specifically request that the Road Force balance be performed - rather than a simple dynamic or static balance. Once that is completed - find a competent alignment shop and have that performed as well.

The fact that it drives straight is not necessarily indicative that the alignment is right. Tracking is but one characteristic of alignment.

As mentioned - there is caster, camber and toe in that must be considered. In the thread at the top of the page - there is a substantial amount of information regarding alignment specs - and how the car is going to be driven plays into that.

http://forums.corvetteforum.com/showthread.php?t=984927 post #3

If the car is used for HPDE, then the specs would be slightly different than it would be for primarily street driving, and the main consideration is to maximize tire wear. The whole idea is to keep the tread flat against the road surface, without placing the weight of the vehicle on any edge.

Shocks are really more accurately described as rebound dampeners, and their job is also to keep the contact patch of the tire on the road surface. If the shock has failed or is failing - it will allow the tire to bounce making intermittent contact with the road surface - which could lead to cupping.

Bottom line - road force balance and a good four wheel alignment is the course of action.

 

It's possible I got a "lemon" shock, but I doubt it is in fact the shock as well.

Any recomendations in Dallas where to go for a road force balance or any web sites to check out. I also heard through all of my research to go to a place that uses the GSP9700 machine to balance. Is the same as road balance?

 

No, they meant aligned also. You need to get the rear as well as the front checked for proper alignment. They should always be balanced when tires are replaced.

 

Do they have Discount Tire or America's Tire in Dallas? I generally have all of my tire work done by Discount Tire here in the Phoenix area and I know the Discount Tire outlets here have the Hunter GSP9700 Road Force machines.....

http://www.gsp9700.com/

I'm sure that there are others in a city the size of Dallas......

 

Yes Discount is actually near by and it's where I planned to go but was curious if the road force balance is something in addition to or different than the GSP9700?

 

 

Good advise by blacksedan87 above.

The Hunter GPS9700 and the road force balance in this context are one and the same. You can also click on the LOCATE A GPS9700 tab at the upper right of the page at the following link to locate shops in your area that have this.

Eliminate Tire and Wheel Vibration with the GSP9700 Road Force Measurement®

Good luck with the balance and alignment.

 

Really.. Rear wells get aligned? How so? Again, this is my first vette so I'm working off convential wisdom and experience where I never got an alignment on the rear wheels. Balance yes..align no?

Can you explain further?

Also, after looking closer this afternoon the inside front left is worn badly where I see threads on the tire. The front right is worn but not nearly as much as the front left. Maybe I do have a bad shock. However I did slam the front left against a curb one time (not paying attention), maybe this threw off the alignment.

 

You may need to get it aligned, and really the only way to get it aligned properly is to get the fronts done at the same time. I like taking my car to a race shop because at the very least, they'll check the ride-height at the same time. If you just do the fronts, the alignment may be in spec, but the car could be teetering like a table with a short leg. If you find a really good race shop, they'll also cornerweight it so the car sits on the ground as level as possible, check the rake, and then do the alignment according to your preferences. I'd go for the Z06 alignment specs as a slightly agressive street setup.

Another reason to get it done at a race shop is that many discount alignment shops don't have the gear to align 18" wheels. Any halfway decent shop will set the alignment once, drive it around, and then check and set the alignment again.....and that's at least once....my last place drove my car at least three times to get it perfect.

 

A sharp impact to one wheel will most definitely throw off the alignment - assuming that nothing is broken (which could very well be). The C5 is a strong car, but a hard enough impact can break suspension components, bend them or knock them out of alignment.

I made reference to an IRS car - by that I meant that the car has an independent rear suspension, and it can be out of adjustment for the same things...camber, caster and toe in. It is imperative that you have all four corners aligned to spec.

A convential car has a solid axle on the rear end - many front drive cars in particular. There really isn't much to align in that scenario - but the IRS is different.

 

Ahhh. I'm with ya now. Good details. Well I plan to go get new tires tomorrow at (I can't beleive I'm going here) but to discount tire. They have they gsp9700 balance machine. Then into the dealership for an oil change and check-up on something else (For those that change their own oil..I know I could do it my self and save money, but it's a time factor for me).

I thought I knew which tire I was going to go with but now Kumho's have been trown back into the mix since they have a 30,000 mile warranty. The popular GY GSD3s don't have a warranty at all and now I'm hearing the max mileage you get out of them is about 15,000. Might make since since there is no warranty. I've heard enough mixed reviews on all of my possible choices/considerations that I'm a bit confussed and starting to think I should simply replace the front OEM GY run flats since the rears still have a good amount of tread left. But I hate the amount of noise these tires produce.

Feels like I'm approaching the analysis/paralysis state of mind..hate when the happens.

Thanks

 

Dont over think it and stress over it. Just find that corvette shop near you.(they are in every state, they can help you find competent shops near you if they are far away) after Discount mounts and balances, take it to the vette shop or to their recomondation and get the alignnment. done good to go..

As I started to read this thread I was going to say just get the proper balance first, see waht happens then go from there. But after reading your responses "cord showing on one but not the other" Id say get the alignment, front and rear, by an expierienced vette shop befor you put too many miles on those new tires.
GL

 

Oh ya, nothing wrong with Discount. got to get tires somewhere, and mounted.

 

As several mentioned above, our C5s have independent rear suspensions and require 4 wheel alignments. The following talks more about alignments along with 4 wheel alignments:

Wheel Alignment

 

That's what I said??? Wheels get balanced and the car gets aligned.

 

If you read VETTESRM's later post, you would see he was refering to a 4 wheel alignment.