NT555 G2 making the ZL1 drive weird
 

Hi everyone,

I own a 2020 ZL1 (non-1LE) that came with the Goodyear Eagle F1 tires.

Recently, I decided to replace my two rear tires as they were almost dead from driving 8000 miles. I decided to keep my front ones as they were in a very good shape, and put some Nitto NT555G2 on the rear.

I chose to put a wider size than the OEM Goodyears that I had before (had 305 put 315).

Ever since I replaced my rear tires, I started to notice that the car was acting weird, which has been confirmed by my friends hopping in the car with me.

On the freeway at around 75+ mph, the car sways/bounces to the side when I switch lanes and accelerate. It feels like the car has a hard time going where I want it to go, it feels much more bouncy than before and the suspension feels floaty and less stiff.

I also took it to the canyons last weekend, where in the past I was able (just in simple track mode) to have lots of fun and have pretty decent grip in the turns.

Now with these new tires in the back, I'm super limited as every corner I lose the rear and the traction control just stops everything. My dashboard keeps blinking all the time I accelerate. I am not an experimented "racing" driver, but still I have a feeling that I'm driving a different car and it's really annoying.

I took the car to the dealer, because I was worried that something else was causing the issue. Maybe control arm, axle, suspensions. They inspected it, took it for a 10 mn test drive and found nothing. Did not even charge me for the time they spent.

I know that I have different tire threads in the front/back, and that I put wider tires. But still, I did not expect this to change so much how the car drives. Also, my PSI now is at 35 everywhere. Used to be really high before with my F1 tires (out of factory usually comes at 41). Also, I drove like 500 miles with these new tires, even did a few burnouts.

Any thoughts ?

This is so weird. So I bought a used 2018 ZL1 last month. It came with the exact same tires only he replaced the front tires as well. So, after I got the car aligned a ton of the sway disappeared. However, after feeling the car out a little more and having a little more drive time post-alignment I feel like it didn't completely eliminate it.

WOT, as you say, right around 75+ MPH the car just feels like its floating at times. I don't feel it otherwise, and it doesn't matter which performance mode I'm in. I've even rotated through the various traction control modes with no luck.

I posted a thread on here about the car and the feel, feel like it pretty much just needed to be aligned with the general consensus but I totally get what you are saying and I have the EXACT same tires on the car. I don't think its a coincidence.

Here's the link to my thread:
https://www.camaro6.com/forums/showthread.php?t=577693

maybe softer sidewalls than OEM? I remember the mistake I made on an old car of mine when I went from Michelin PSS's to Hankook V12's my car suddenly felt like a boat and the handling went down the tubes. Couldn't wait to get PSS's back on.

Damn, thanks for sharing your experience. So you got the car with four NT555? The dealer said I did not need alignment, but maybe I will take it somewhere else to do it anyways. Its really scary sometimes.

Someone also told me about the softer sidewall hypothesis. With the stock tires, the car was so steady and I was always impressed with how it could handle anything with so much precision. But you're right, that could explain, and also the mix of harder sidewalls on the front, softer on the back.

My mother in law listened to her Mazda service advisor instead of me (22 years exp as a service advisor) about tires on her Mazda6. She recommended to her to put Yokohama Advan Sports on it for a little less money. I advised her to stick with the Bridgestones that came on it since they lasted 40k miles and she loved how it drove. Or go with the Michelin Pilot Sport AS3. She put the Yokos on then drove to my work demanding I drive it a few days later. You know why. She traded the car for a new Mazda6 a few months later.
I would have to say you going wider also made the sidewall taller unless you went a series shorter. That in conjunction with that tire's performance level caused your sidewall to deflect even more.
I tell my customers at work who are actually in tune with their vehicles to stick with what came on it or I will recommend what I know to be a "better" tire. I always say if you liked/loved how it drove before, buying a different tire could change that feeling dramatically.

malvada, just a guess, but any chance you put on 315/35 tires instead of 315/30? That would explain the floatiness and weird traction control behavior, because they're 5.5% taller than your OEM 305/30 Goodyears and leaving the fronts at stock size introduced a significant mismatch if that's the case.

In general, as you already know, tires with different compounds from different manufacturers in the front vs the rear are always a risk, grip will be different at various temperatures and pavement conditions, so the car's behavior becomes less predictable at best.

Probably the biggest difference you are feeling is run flat GY’s have super stiff sidewalls while N555 G2 are softer. I put Nittos on from stock Goodyear’s and yes, you give up a bit of handling precision, but worth it for me cause I don’t have mag ride and my fillings were coming loose with the run flats.

So you have two different sets of tires on the car and the rear ones are wider than the stock size to boot? Zero surprise you are experiencing wonky handling. The suspension is designed to work in concert with the stock tires and sizes.

I have no doubts your problem is due to mixing brands between the fronts and backs. I run 315s on the rear (30 aspect ratio) with no handling issues whatsoever. Fronts are OEM size.

Put NT555G2 on the front problem solve you cannot mix brands for DD if you were in a straight line no difference. Any good tire dealer will tell you that see what I wrote GOOD TIRE DEALER. The front is grabbing and the rear isn't or the other way . You cannot mix tires.

Never skimp out on tires. They are more important than you think.

I’m going with this.

I’ve been in a few cars with RF’s in the front & drag radials in the rear & it felt similar to what OP described.

It’s similar to having radials in the front & Bias plys in the rear. Decades upon decades no-no unless you know how to drive it that way & have learned to anticipate it.

Thank you for all your answers.

That might not be an alignment issue then.

Someone asked and my NT555 are 315 30 and not 35.

Mixing tires wasn't the best idea, it's true.
It sucks because these NT555 are brand new. My next set will definetely be the OEM GY again.

Check the alignment. Had similar issues