Experience with GTS size PSS tires on a stock ZCP car?

For those who haven't seen my other thread, I purchased an allocation of a custom run of wide Avant Garde m359 wheels to run wider tires on the car. I'm on the fence on keeping the wheels due to various issues, and am exploring alternatives, namely GTS Tire Sizes (255/35/19 front 285/30/19 rear) on my old factory zcp wheels.

When I made the decision to pursue the wide m359 wheels (2019), it was because my intended tire was the Michelin PS4S, and the widest tire you could reasonably run on a factory zcp car was a 275/35/19, as a 285/30/19 is not available as a PS4S, only a PSS and a 285/35/19 rubs. Many tire manufacturers don't recommend a 295/30/19 on a 10" wheel.

Anyway- fast forward to 2022- and Michelin has just started selling the PS4S tire in 285/30/19, meaning you can get factory GTS tire sizes in the PS4S front and rear finally. An option not previously available to me. My best guess is that previously, a 285/30/19 was a very uncommon tire size, but I noticed the other day that the C7 Z06 corvette has a 285/30/19 front tire stock. That alone could have caused more products to come out in that size.

So now I am exploring the option of returning to my factory ZCP wheels, and putting on GTS tire sizes in PS4S tires. (255/35/19 front and 285/30/19 rear) As I've learned some lessons along this journey, so asking these questions here just to be extra sure. As the PS4S tire shape is similar to the PSS tire- this is the best sample base I can pull from. So if you ever personally ran PSS tires in a GTS tire size on a factory ZCP car, these questions are for you:

1. Any rubbing? Yes seriously. One of the lessons I've learned here is to ask about rubbing with a specific tire model, as tire models vary in size within a size. Also, as far as I know, the GTS did not come with PSS tires, so this information is helpful. The wide shoulders of the PS4S tire burned me once. This question has a clear answer of no rub on the forum for the fronts, but much less info on that rear size.

2. How would you compare the driving experience from stock tire sizes? I'd be interested to hear about regular every day street driving and long distance cruising specifically, as well as canyon carving and track.

3. Regrets?

I have the GTS tire set up but honestly it's only because the Conti tires don't come in 295/30/19. I am on Ohlins r&t at suggested ride height which I believe is like a .5" drop or something ( more so in the front as they recommend rake) You might experience rubbing with the front tire near full lock in parking lot situations. This is common and most people pretend this size doesn't rub. No issues in the rear due to its smaller diameter. Wheel offsets are +21/+22 9.5/10.5 F/R. I can't compare stock sizes but I do prefer how the rear feels with the 285/30 over the 275/35 as I get slightly better traction and it feels more controlled when it breaks loose giving better feedback. This is all minimal though so its not something you'll feel unless you're pushing the car hard. No regrets and I love the Conti tires more than the PS4S because the performance is identical but the prices are not

I run 275/30 and 295/30 PSS on ZCPs and had asked whether the PS4S in these sizes still fit, and the answer was "yes": https://www.m3post.com/forums/showthread.php?t=1723647

So, I don't see the 285/30 PS4S being an issue.

Edit: I actually see you had responded in that thread

@jra85 do you have spacers? What type of camber set up?

nycplumber wrote

@jra85 do you have spacers? What type of camber set up?

Stock ZCP everything, it was strictly just a tire size change. Had very slight rubbing on the rears over larger bumps when I first put them on but at this point (~10k miles later over about 10 years) it's gone. I can understand the desire to go with 285s or narrower on the M359s though. I strictly do street driving and prefer the wider look.

I'll add my 2 cents. After installing a set of F80 M3 brakes, I realized that even my square 219MS didn't fit so purchased a set of lightly used 359Ms with PS4S tyres. 255/35/19 on the front and 295/30/19 on the rear. The rear does rub under heavy compression and the fronts rub slightly on full lock, I believe there are now Michelin Cup 2 track connect BMW * tyres available in GTS sizes now and I'll go for those next.

nycplumber wrote

I have the GTS tire set up but honestly it's only because the Conti tires don't come in 295/30/19. I am on Ohlins r&t at suggested ride height which I believe is like a .5" drop or something ( more so in the front as they recommend rake) You might experience rubbing with the front tire near full lock in parking lot situations. This is common and most people pretend this size doesn't rub.

This is interesting. You mentioned the ride height- is that a .5" drop from zcp ride height, or a .5" drop from regular ride height?

I was under the impression that 255/35/19 PS4S on a stock zcp car with zcp wheels did not rub. So many people run a 255/35/19 front 275/35/19 rear upgrade, but I don't recall hearing rubbing complaints.

The people pretending this doesn't rub comment has me concerned. Great information.

Gouki wrote

I'll add my 2 cents. After installing a set of F80 M3 brakes, I realized that even my square 219MS didn't fit so purchased a set of lightly used 359Ms with PS4S tyres. 255/35/19 on the front and 295/30/19 on the rear. The rear does rub under heavy compression and the fronts rub slightly on full lock, I believe there are now Michelin Cup 2 track connect BMW * tyres available in GTS sizes now and I'll go for those next.

Curious, what is your suspension setup? Stock ZCP?

The fronts rubbing slightly on full lock is concerning.

I think you're overthinking this lol. Just put the tires on and if you don't like the set up then switch it

I have stock ZCP suspension and GTS size wheels and tires. I've tried many different tire sizes on the back (285/35 and 295/30) over the years but am now at 285/30 and in my opinion this is the optimum size for the back on a ZCP car. Fronts are 255/35 as per GTS spec. My current fronts are PS4S and backs are PSS due to the lack of 285/30 PS4S at the time of purchase. There was very minor rubbing at full lock on the front but this has gone away. I found the 285/35 (Conti DW) and 295/30 (PS2) to feel "squirmy" in high speed corner transitions but the 285/30 feels more stable. Could be the difference in tire make/model but I'm very happy with my current tires at the moment. If a 285/30 PS4S is now available, I will change to that next.

hotbmwfan wrote

I have stock ZCP suspension and GTS size wheels and tires. I've tried many different tire sizes on the back (285/35 and 295/30) over the years but am now at 285/30 and in my opinion this is the optimum size for the back on a ZCP car. Fronts are 255/35 as per GTS spec. My current fronts are PS4S and backs are PSS due to the lack of 285/30 PS4S at the time of purchase. There was very minor rubbing at full lock on the front but this has gone away. I found the 285/35 (Conti DW) and 295/30 (PS2) to feel "squirmy" in high speed corner transitions but the 285/30 feels more stable. Could be the difference in tire make/model but I'm very happy with my current tires at the moment. If a 285/30 PS4S is now available, I will change to that next.

Awesome information!

I'm assuming the spot that was rubbing on the front was the rear of the front fender liners. Did it rub all the way through the fender liner, or did it just thin it out a bit? Any chance you could snap a picture? The exact rub spot would be helpful to know if massaging the fender liner with a heat gun would help mitigate it all together. Some common rub spots have metal directly behind them, so there isn't alot you can do there.

The rear front fender liners require pulling the strut to replace, so kind of clunky.

Here is a pic. This only happened on the passenger side liner. It is very minor, basically just polished the back of the liner. Nothing on the driver side.

hotbmwfan wrote

Here is a pic. This only happened on the passenger side liner. It is very minor, basically just polished the back of the liner. Nothing on the driver side.

Interesting. That spot would indicate that the rubbing was not actually at full lock, but more like at 50-60% wheel turn. All to familiar with that rub spot. There is hard metal behind that spot, basically nothing you can do to massage it with a heat gun.

Secondly, that spot has not dirtied back up, and is still shiny, which implies you are in fact still rubbing. When I cured my rub in that spot, it was covered back up with dirt within a couple of weeks and not very many miles.

How long have you had the tires on, and how many miles?

These front tires were purchased in May 2017 and have about 6,700 miles on them. They're scheduled for replacement this spring, so the rubbing may come back with new tires - but I'm not going to worry about it.

drwankel wrote

Curious, what is your suspension setup? Stock ZCP?

The fronts rubbing slightly on full lock is concerning.

Stock ZCP EDC

Gouki a écrit

EDC ZCP d'origine

C'est pour ça que la GTS d'origine est livrée avec des cales de 5 mm à l'avant ? T'as roulé sans cales ?