WhiteKnight '01

Recently put on 250 60 16's on my car, they are the Firestone Firehawk Wide Oval Indy500 tires,max performance summer tires, pretty much the top tier tire that Firestone sells. I've read the reviews, people with BMW's, Firebirds, Camaros, Corvettes, mostly RWD cars, and everyone has great things to say about these tires. My previous tires were some cheapo Fuzions, Summer performance tire, but nothing special.

My problem is, when crusing at highway speeds, 60-75MPH and I tilt the wheel to the left or right a little bit, the entire back end sways, it takes forever to correct and keep up with the nose. It feels like I'm driving a minivan. If I want to make a quick lane change, I'll have to wait at least a couple of seconds for the rear end to catch up with the rest of the car, before this the car was very nimble and could swap lanes very quickly.

The tires are not very confidence inspiriing. Driving in excess of 80MPH is actually pretty scary now, the slightest tilt of the steering wheel and it feels like the car may veer off the road, can't think of a better way to describe it, other than the back end is slow to keep up with the front end. Drive a minivan at 70MPH and wiggle the steering wheel and it kinda feels like that.

My question is, it is the tires causing this? Or could it be a suspension problem that has been intensified with newer tires?

My ideas on things it could be, please correct me if I'm wrong or offer more adivce.

1. Tie-Rods
2. Pan-Hard bar
3. Front and/or rear sway bars
4. Alignment (although I had them do an alignment after installing these tires)
5. Worn out bushings or a fautly axle.

Please, any ideas on what this can be? The closest thing I have found is it could be the pan-hard bar, but I can't be sure. Any ideas or advice?

3 pedal SS

iTrader: (1)

Just a WAG...check tire pressures> Adjust them perhaps. Check your anti sway bars/bushings. In need of shocks?

therabidweasel

iTrader: (5)

Do you know your alignment specs before and after?

01ssreda4

iTrader: (96)

A 60 series tire that doesn't sway on the hwy? Does that exist? That's a ton of sidewall. Try airing them up some. That stiffens them up and controls the feeling you are having.

SladeX

That's too much sidewall. You've gone to an almost 28 inch height tire. Raising air pressure can only do so much.

TA_Freak

WhiteKnight `01,

I have the exact tires on my TA and I too have been scratching my head for a while trying to find out what could be wrong with my car. I have a ton of suspension upgrades and now that I am reading your post, I am convinced that these tires are crap. Sorry to be so blunt .... but it's true. I had the same size, sidewall (255r60x16) on the G-Force Sports and they were a million times better.

WhiteKnight '01

Hey, something I figured out. Like an idiot I actually trusted the tires to be propperly installed by the guys at Firestone. Turns out the rear left tire was set at 46PSI and the other 3 were set at 40PSI. On the tire itself it says, do not exceed 40PSI. So I lowered them to what my previous tires were at, about 32PSI. Car handles MUCH better now.

Second thing I've noticed is when it's hot out, these tires get a little wobbly, they still do better with 32PSI in them. But then at night, when it cools off, they are sharp as hell. Feels like I'm driving on rails. I still kind of feel like an idiot for not checking the tire pressure. But still, other upgrades and maintenance need to be done to my car.

TA_Freak

Interesting. I have mine at 36 psi right now - I think. I will lower them to 32 tomorrow and see what's what.

z28bryan

iTrader: (7)

I got confused because I thought I answered this thread before, but turns out you made a second one. Reference to this thread for more info: https://ls1tech.com/forums/suspensio...any-ideas.html

So what do you have for a tire size? The stock 245/50/16 or a 250?/60/16? I'm guessing that 60 sidewall size you mentioned is a typo. If it's not though and you did get a 60 series sidewall then you've possibly increased your overall tire height by 2 inches.

Either way you said in your previous post you always had this problem.. you previously ran fuzion tires. I'm still going "all in" on it being your tires. Unless you can rule out loose bushings on your control arms, PHB, any linkage.. then I'm voting on tires. The wide ovals have a lot of reviews about rollover being common.

If you want to stick with the 16 inch wheels, there are plenty of tires out there that will handle better.

Also I don't understand how lowering air pressure will make the car handle better or more predictable.. more pressure will increase the response of the tire... unless you are actually losing traction on the higher pressures then lowering your pressures will only make the tires rollover more. ~32 is a normal tire pressure though for many applications.. you shouldnt have to increase your tire pressure near 40.

z28bryan

iTrader: (7)

Do you have access to anyone who has some 17 inch wheels and tires? If you do, will they let you put them on to see if you can rule out the tires being the culprit?

SSCamaro99_3

iTrader: (1)

Too much air pressure will make the tires overly hard and bouncy. I had a shop put 45 psi in a set of tires one time. I was driving on the highway and it felt like I was riding on basketballs. More air pressure will also increase your effective spring rate.

TA_Freak

That's what I thought until I lowered my Firestone's from 36 to 32 today. Tracking was much better as the tires absorbed the road's imperfections. Handling was also much better and predictable. It wasn't so much "work" to drive the car today as it has been. This is my DD and with all the money and work that I've put into the suspension, it was a shame to have it perform as it did. The lower pressures in the tires did away with the rear oversteering feeling/condition.

bwkmaro

fuzion tires have a stiffer side wall than the firestones its not just in ur head your car prob handles better just looser going in or out

MeentSS02

iTrader: (11)

Too much or too little pressure will change the tire's contact patch...this is one of those things you want just right for street driving.

WhiteKnight '01

That is the exact feeling I had with my car when my tires were first put on. It swayed so much in the rear end it felt like I was driving a minivan, and I hated it. Lowering it to 32PSI for me helped immensely. At night the car feels extremely sharp and nimble, and far better than my previous Fuzion tires. During the day time, it's just a tad sloppy. I might try lowernig it to 28 or 30PSI, see if further increases can be made.

WhiteKnight '01

The Wide Ovals have a lot of mixed reviews. Many people who drive performance oriented cars, I.E. Camaros, Corvettes, Mustangs, BMW's, mention they really like these tires, while some other mention the softer sidewall, and since I'm not a huge performance enthusiast, I didn't think it'd be a big deal.

As I mentioned earlier, I've pretty much solved the problem. The people at Firestone set my rear left tire to 46PSI and the other 3 to 40PSI. After reducing it to 32PSI the car feels perfect and these tires handle better than my previous Fuzions did.

Also, if you don't think increasing or decreasing tire pressure can affect handling, why don't you try it? Increase your tire pressure by 15-20lbs or decrease it by 15-20 lbs. Also, when you have a flat tire...you can feel it in your handling. Car feels much better now, but I may pursue some other suspension upgrades, Tower Strut Bar, Pan-Hard Bar, and Sway Bars, not sure which or in what order though.

TA_Freak

Really glad that I saw your post, WhiteKnight '01. That's crazy that Firestone would have had the pressures like that. I will take note of how it drives this evening on my way home from work ... it will be much cooler than coming in.

I have put a fair bit into the suspension in the last 5,000 miles:
stranos/billsteins (lowered), rear LCA reloc bracket and tubular LCAs, double adjustable panhard bar, strut tower brace on the front and all new poly end links, new rack and pinion and tie rod ends.

WhiteKnight '01

Glad I could help. Any news on how it drives at night?

TA_Freak

Much tighter, stiff and bumpy when cold. I still don't care for the tires, but it is night and day difference from when when they were at 36 psi.

WhiteKnight '01

Do you have 16 or 17 inch wheels? I'm still running the stock 16 inch snowflake wheels on my Camaro, they're ugly as hell and the tire selection for them is poor. The Firestone tires were one of the better tires available for the price. I've noticed the 17 inch wheels have a huge selection of performance tires, but all are much more expensive.