315-30-19 Michelin Cup 2’s on a 15 Z/28?

[The_Raging_Bull]

The title says it all: has anyone run 315-30-19 Michelin Pilot Cup 2’s on their Z/28??

It’s been a while and my tires are officially toasted, so I thought go ahead and put 315’s on if possible >> and they fit correctly in place of the normal 305's, I’ll add a spacer (1/4” or 1/2" if necessary), but was hoping someone has run one size up on the Michelin's on their Z, and I could learn from someone who has already done it.

The 315-30-19 size runs 28 pounds per tire, so a couple of pounds heavier than the 305-30-19 Trofeo-R’s which I STILL have on at 6200 miles-> which are at 2-3mm of tread left…looking like slicks.

Anyone who has experience with the Cup 2’s or Michelin's where the sizes are close, and how they dealt with it, please jump in and give me some advice. The 4S's are only in 305 or 325, and I don’t want to go 325, as the extra un-sprung weight will help change the nimbleness of the handling of the car. All of you track guys give me your best shot at some advice. If necessary, I’ll add ¼” plates to help push the tires out slightly to make them fit; as I’d think that the 315’s will allow the Z/28 to match the 315 width on the flat plane mustang Shelby; and give much better grip.

That said, all help is appreciated, I’ve got time to let the thread run two or three weeks before I pull the trigger on new tires.

Larry

[FLOW TIE]

Larry,
It looks like Jeff runs 325s.
They actually don’t look “tall”. I’d guess the 315s would look pretty close/a little beefier than stock Trofeos.

https://wheelwell.com/jeff-drinkard/...cd150f112a1eaf

[The_Raging_Bull]

Originally Posted by FLOW TIE

Larry,
It looks like Jeff runs 325s.
They actually don’t look “tall”. I’d guess the 315s would look pretty close/a little beefier than stock Trofeo-R's.
https://wheelwell.com/jeff-drinkard/...cd150f112a1eaf

Chuck That was my feeling. I'm going to buy a couple of the rear rims this year and then have a set of spacers cut down to the absolute minimum needed. I'll do that later after the fact. Based on what I've seen in my search I can use either 315 or 325. If I'm careful and buy the new rims, I shouldn't have issues, but CAN run the standard fronts with 325's; just don't go tearing down rough streets as one of us reported bubbles on his 325's when on rough streets.
It also seem like I need to buy either 5 MM or 10 mm spacers in the front to allow rotation >>>> especially after you upgrade to rear rims in the fron. From the various wheel/rim - tire forum threads the extra width from the use of the wider rims on the front rims/tires on the Z allow the rims to slightly touch the DSVV shock body. creating a small amount of metal being removed as it is "haved " off.metal being shaved.


315 width....on standard OEM rims...fit no issue.
315 width on rear rim (installed on front)...no issue of fitment, add spacer to rotate


325 width fit on standard rim front used up front..add spacer, slightly wider than optimal.
325 width fit on rear rim front used up front..add spacer, slightly gr8 fit.


On both the spacer prevents any wear of the wider rear rim, since it can touch the DSVV shocks and shave a small ribbon of metal off the rim-DSVV touch point.I'll put together a comprehensive list of tire brands, sizes and how they interact with rims. If anyone want to add aftermarket rims, please do it after all the OEM rim information with various tires sizes & brands are in.
when you upgrade the front rims to a pair of rear rims in the front, a;ways use hub-centric spacers too to avoid any issues where the spacers are misaligned or they can touch the DSVV shocks.
Has anyone measured the Exact width spacers needed for the standard front rim, and th exact width needed if you use the wider rear rims?
I'd like to make the best custom width spacer possible for optimal fit. As you and others feel..and I agree with others ...the spacer (with both the standard front rim, and the rear rim used in the front) allow you to rotate the rim/tires..while keeping tire wear minimal and preventing any damage from the rims touching the DSVV Shock Body.

On my 09 Z06 as an FYI, I'm at 6200 miles on my Pilot Cup 2's w/zero appreciable wear, so 17,000 to 22,000 miles is entirely possible with the pilot Cup 2's. I don't drive them in the rain in the siummer or cool weather(never less than 45F) In winter the car (both '15 Z/28 and 09 Z06) is stored with the wheels/tires off the floor on roll-around floor jacks, so the tires cant get a flat spot on them.


And Yes Virginia The Michelin Cup 2's corner like a scalded dog on my 09 Z06...zoom zoom zoom!!!!!!! I'mn runnign 295 width in the front and 345 width in the rear.

[pat_t]

Originally Posted by The_Raging_Bull

...Has anyone measured the Exact width spacers needed for the standard front rim, and th exact width needed if you use the wider rear rims?

I have pushed the front fitment pretty much as far as it will go.

You need to know the following:

You can't answer your question without knowing what front camber you want to run, with more negative camber the tyre gets closer to the DSSV shock.

Without longer front wheel studs, or one of the bolt on hubcentric spacers that uses new studs and fastens to the upright using the original studs and nuts, you can't get a rear rim on the front.

A 325/30/R19 Pirelli Trofeo R will fit the OE front rim and is fine on street and track in my experience. This will work at maximum negative camber but only with a 6mm wheel spacer.

A 6mm spacer is the thickest you can fit and retain the OE wheel studs due to losing thread engagement.

A 6mm spacer is the thickest you can fit and retain the OE wheel hubcentric engagement due to losing hub protrusion.

If you go thicker than 6mm you will need hubcentric that tend to start at 15mm, maybe 14mm if you are pushing it. Therefore it is impossible to fit a wheel spacer in the range of 7mm to 13mm on our cars.

The Michelins you describe should run fine even at max meg camber because even the 325 Cup tyre runs narrower than the Pirelli.

If you fit or have adjustable camber top mounts you can switch up what I've written. You can use the top mount to give you neg camber, and adjust the strut slot for more tyre-to-DSSV clearance.

Hope it helps buddy.

[The_Raging_Bull]

Have you got a suggestion on adjustable camber plates? Moreno Motorsports was. Making them.Among them I guess when I’m off the phone tonight I’ll look them up. Are there others anyone can suggest?

[ronchev]

Originally Posted by The_Raging_Bull

Have you got a suggestion on adjustable camber plates? Moreno Motorsports was. Making them.Among them I guess when I’m off the phone tonight I’ll look them up. Are there others anyone can suggest?

Moreno camber plates are now being made by Gen5diy that is on here alot

Following this thread for the larger sized street tires, this is something that I want to look into as well

[Biergut]

Originally Posted by The_Raging_Bull

Have you got a suggestion on adjustable camber plates? Moreno Motorsports was. Making them.Among them I guess when I’m off the phone tonight I’ll look them up. Are there others anyone can suggest?

+1 and plates that do not raise ride height and do not need to be customized in order to work with the DSSV units...

[The_Raging_Bull]

Thanks, Biergut...I ordered the tires tonight, I've been in DFW all week. I've got a set of Bontrager tubulars up on eBay to cover the cost of the Moreno Gen5DIY adjustable camber plates.

[The_Raging_Bull]

well..
I pulled the trigger on 4 Michelin Cup 2's @ 325-30-19's $2144 and change at Tire Rack. Will be mounted this Saturday..I can't wait!
Pictures to follow!

[pat_t]

Originally Posted by The_Raging_Bull

well..
I pulled the trigger on 4 Michelin Cup 2's @ 325-30-19's $2144 and change at Tire Rack. Will be mounted this Saturday..I can't wait!
Pictures to follow!

They're gonna look great!

[The_Raging_Bull]

Originally Posted by pat_t

They're gonna look great!

pat what size and which michelin tires do you use? if they are cup 2's how about psotign a pic of a 325-30-19 if thats what you're using.

[pat_t]

This is a 325/30/R19 Michelin Cup+ N2spec (not Cup2) mounted. Taken when I got an alignment just before driving on them all the way to Nurburgring, lapping, and then all the way home again including getting caught in an October blizzard!



I'm very impressed with them. 90% of the outright dry grip of the Trofeos, but about 150% of the wet grip with only 50% of the wear!

I'll be fitting either the same again or Cup 2s when this set is done.

When you get yours have a look to see if they have 'N0' 'N1' or 'N2' printed on the sidewall. If they do it means they are "Porsche approved" which basically just means Porsche did a whole bunch of additional development work on them to ensure they meet the criteria for fitment to 911s and 918s.

[FLOW TIE]

Larry,
Did you get them installed yet?

[oakaro68]

So if using the 325s on the rear wheels, in the rear, do you need spacers or no?