groundhog

The weight ratings are different on rears, e.g. the 305 is 103Y and the 325 is 108Y.

JCR-Porsche

I might suggest educating yourself a little further before calling people idiots

JC

JCR-Porsche

Nice quick edit removing the 'you're an idiot'

If you take a look at the title of the thread - Michelin Cup 2 R K1 (Ferrari Spec) on GT3? - We're discussing the GT3 tyre vs the same size Pista Cup2R.

I think you're getting a little confused with GT3 RS sized tyres. No one ever mentioned GT3 RS and comparing a different sized tyre has absolutely no relevance to this thread.

JC

SterlingatBOM

Search K1 and orthojoe and you’ll have your answer.

mrhamamg

i searched k1 in entire posts for orthojoe and nothing came up

Seth Thomas

This is not 100% true. Tire manufacturers do build different spec tires for different car manufactures. Case in point is Pirelli. While I was working on a program with McLaren North America the 650S was brand new and we would take all the cars to the track with the Pirelli P-Zero Corsa tires. The fronts were a 235/35/19. For our second track day we were sent a pallet of the Corsa front tires but they were the standard Corsa and not the ones with the MC1 stamped on the side. At Monticello Motor Club the cars were all over the place under braking. The rear end squirmed under the dive of the front end. If any of the cars still had a the MC1 tire on it the squirm was not there. You could back to back drive the cars in this configuration and could immediately tell a difference. If you looked at the tires and the specs on the sidewall there wasn't a single difference other than MC1 stamp on the tires that did not have squirm. From that experience I can tell you there is a difference in the proper manufacturer spec tires on a car when on the racetrack. For the street I don't believe it would matter as much but on the track it was a big difference.

3Series

Can you explain what the point of that is? A 325, 305, 295 wide tire will fit on a 12in wide wheel. Hoosier R7 tires are wider tires and they still fit.

ipse dixit

https://rennlist.com/forums/991-gt3-...l#post12077071

JCR-Porsche

I don’t doubt that at all however that’s missing the point of what I was making in regards to this specific application and tyre.

The variation between Pirelli tyres set to set is also something to be considered

JC

3Series

That's exactly marketing for you. The manufacturer has to make a slight variation to legally call it a different tire model. For most track day enthusiasts, do you think it's worth 20,30% premium??? Your description makes it sound as if non-MC1 tires are absolutely garbage and unsafe on a McLaren. Is it? Doubt it. Maybe your braking style is different....lots of variables. I've driven with SC2's and Trofeo R on the same car and it's very subjective for a track day enthusiast and that's your target market. These aren't racing tires used for racing so the variation is used for marketing and it's essentially the same tire. That's the point folks are trying to make.

At a track day, folks will vary on, I like this tire or I like that tire.

On a forum, folks think if they don't buy the right tire, the car will fall apart driving to the local McDonalds taking the "fun" route.

groundhog

I suggest you look at the different weight ratings for different tire sizes in the Porsche range of sizes - there are a lot of tires and a lot of those don't have the correct weight class. Putting the wrong weight class tires on your car is bad news particularly in regard to the rear. Moreover there are clear differences between the N ratings even within the same size group - which can relate to change in compound, sidewall protection and even tread variation. Furthermore, different manufactures have different specs for the same tire group - so an AM, MC, N or K stamped tire may still be called a Cup 2R or Cup2 (or 4S) however there are differences sometime minor, sometimes significant. I know for a fact Porsche and Michellin will through some 800 test tires before they settle on a specification. Sounds like its you who needs the education.

groundhog

You are wrong. Plain and simple and the faster you go the more wrong you are.

mrhamamg

Thanks but this refers to the previous spec Cup 2 not the Rs. In March 2019 Michelin revised their K spec for the 488 Pista so its a Cup 2 R now which is the same compound supposedly as the GT2/3RS Cup 2 R but in normal GT3 fitment.

JCR-Porsche

So the load ratings were critical until I proved they were the same and now they mean nothing?

I’m not arguing that tyres differ size to size between applications but again, we’re talking about a very specific application here. Not Mercedes, not McLaren. In this specific case there isn’t a difference.

Im not writing these things to be edgy or come across clever, I’m answering a question that the OP asked based on knowledge coming from the horses mouth.

Maybe we will have to agree to disagree on this one

JC

groundhog

Sure..............you think the K1 are the same as the Nx in everyway - even tho they can and do have different compounds, can and do have different sidewall, tread and wet characteristics etc, have at it.

Thats why I don't listen to people like you - it works like this, you fit what I say to my car in the way that I want it. If not, I go somewhere else. Why, because I've done a lot more of this than you.

As a comment to your offerings on your website - perhaps you should get some body kits for dimwits from canary wharf, perhaps offer a Cxxx tune