Crazy oversteer / wheelspin with Michelin Pilot Super Sport

[7thgear]

Originally Posted by 4032pauln

I think the max psi for this car is supposed to be 35

tire pressures are not absolute nor are they directly and solely derived from the mark of your vehicle

air in a tire is there to give the tire carcass rigidity,


air pressure is set depending on the tire construction (brand), the volume of air, the vehicle weight (load), ambient temperatures and intended application.



and why is ubersuber not banned yet?

[BRZZZZZZZZZZ]

Are they literally brand new? Tires need to be broken in to get the manufacturing oils etc out of them and that usually takes 300-500km of driving too.

[stonenewt]

IIRC MPSS have really stiff sidewalls, this means they're going to make the suspension stiffer. Running them at very high PSI will make them even stiffer & a stiff rear end tends to make for oversteer.

[stonenewt]

IIRC they have really stiff sidewalls so they effectively stiffen the suspension. The stiffer you make the rear end the more you'll oversteer. It's also worth noting that MPSS are dual compound with most of their cornering grip being delivered by the outside shoulder of the tyre. Over pressure will reduce shoulder contact & run on the harder centre compound. In short running high pressures in MPSS is a quick way to losing a lot of grip!

FYI - I found that bumping the tyre pressures up by 3PSI all round on my 1er makes for great 4 wheel drifting fun. I run my MPSS at -2PSI from the sticker on the door for optimal grip.

[Akari]

To add to what everyone else has said, these tires do like a bit of heat. Driving at 37psi on a cold road without warming them up at all will definitely result in this type of feel. The stock tires are insanely progressive when they lose traction, and while the MPSS are still pretty good about this, they do like to give a bit less progressiveness IMO.

The maximum grip I've found is at 32 PSI with a warm up lap on warm track asphalt.

[tomkozski]

Are the tires installed on the rims correctly, meaning are they facing the right direction, since they're assymetrical?

[wparsons]

Originally Posted by BRZZZZZZZZZZ

Are they literally brand new? Tires need to be broken in to get the manufacturing oils etc out of them and that usually takes 300-500km of driving too.

or about 200km's on the street + half a 15 minute lapping session

I picked up new tires Saturday, was out lapping on Sunday. I knew they would be greasy for the first bit so I was expecting it, but man could I feel the difference once they were scuffed in. Last tires had over 1000km's on the street before they saw a track.

[BlaineWasHere]

Originally Posted by BRZZZZZZZZZZ

Are they literally brand new? Tires need to be broken in to get the manufacturing oils etc out of them and that usually takes 300-500km of driving too.

I'm guessing this.

[Simon99]

Originally Posted by D_Thissen

Camber bolts for the real eh? Do you have a p/n?

Originally Posted by Ubersuber

Recommended tire pressure is 35 psi, no reason to run any different pressure. Certainly lowering tire pressure will not improve tire grip.

How green are your tires? Check the DOT manufacture date for tire age (fresher is better but they will be greener to begin with) and how many miles on these tires?

Green tires are not very grippy no matter what make or model they are. Mould release needs to be scuffed off and the tread surface scuffed up. Heat cycling isn't a big factor with street rubber but it will make some difference especially with these ultra high performance tires.


One more thing is the factory alignment often isn't any good. Mine was out of spec from the factory and required camber bolts to reach correct spec. Subaru has a part number for camber bolts for the rear LCA so that tells you something. Probably an Impreza part number.

Put 2,000 miles on the new tires and then check back with us.

+1 on that, never heard of camber bolts for the rear but if it exists I require part number !

[Ferrari]

The tires now have 5000Km on them, so they are not green anymore. They are all installed correctly, I checked. The alignment is good as well.

I will drop the pressure to 34 PSI to see if that makes a difference. Again, these tires almost never get any temperature in them since I drive short distances to work at very moderate speeds.

I just expected more grip than this. I used to have Toyo T1-S on my old Honda Prelude and they were very sticky even when cold.

Thanks for all the replies!

[Ferrari]

Originally Posted by wparsons

or about 200km's on the street + half a 15 minute lapping session

I picked up new tires Saturday, was out lapping on Sunday. I knew they would be greasy for the first bit so I was expecting it, but man could I feel the difference once they were scuffed in. Last tires had over 1000km's on the street before they saw a track.

wparsons, how were the MPSS on the track? Are the tires still useable on the road? I was supposed to go to the same track day at Mosport on Sept 7, but had to cancel due to work.

A few years ago I used a set of Michelin Pilot Sports on the track and they were absolutely destroyed after one day.

[EAGLE5]

Primacy ride smoother and quieter than MPSS. MPSS grip better when cold from my experience and, according to OrthoJoe (I think), about the same when up to temp. I'd knock them down to ~32psi all around and see how it feels.

Brand new, though, the MPSS grip like butter on a muffin. I think might got better after at least 100 miles of canyon driving. The ride home from the tire place was white knuckled as they squirmed all over.

[Malt]

Originally Posted by Simon99

+1 on that, never heard of camber bolts for the rear but if it exists I require part number !

They exist. H&R Triple C camber bolts http://perrinperformance.com/i-13324...-14mm-dia.html

They install in place of the inboard rear lower control arm bolt but don't be surprised if you don't get much adjustment. I got ~0.3 degrees of adjustment out of them. You'd be better off just getting a set of quality LCA's and be done with it.

[wparsons]

Originally Posted by Ferrari

wparsons, how were the MPSS on the track? Are the tires still useable on the road? I was supposed to go to the same track day at Mosport on Sept 7, but had to cancel due to work.

Wouldn't know, my last tires were Dunlop ZII's and the new ones are Hankook RS3's.

If you're ruining tires after a single track day, you're over driving them by a lot. My ZII's lasted almost two full summers (would've lasted longer if I hadn't driven for 3 months with 1/2" of toe out up front) and 8 track days, plus a couple autox events.

Too bad you couldn't make it on Sunday, it was a great day! Did you transfer your spot to a friend? I was checking people in and think I remember someone mentioning they took a spot from a friend that was stuck working.