Newfound bodyroll with the brz
 

I have a '15 brz with about 65k miles on it and I have done no suspension related changes except maybe the sti tranny mount if that counts. The problem is that the first set of tires the oem primacy and also the evo 2s from hankook felt beter going down the on off ramps than my current michelin pilot super sports. I did go slightly wider at 225/45 r 17 on oem wheels for the Mpss. It feels not as flat and stable around the corner than I remember and I was wondering if anyone could recommend me a solution. Is it the wider tires that is throwing me off or maybe worn bushing that need replacement or is it just my imagination? I have been on the mpss for maybe 7k miles. Im still inflating at 35 psi cold. Thanks!

P.s. My hankooks ran into a pothole on the highway at night and two of them had sidewall damage so I had to switch. I wanted to get the best dd tires because I wanted them to last longer and be more fun.

Could be the stickier contact patch. They could be reducing the tire slip, which is transmitting the load to the suspension now, inducing more roll.

Beat me to it..

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I put on 235/45-17 Pirelli PZero A/S (25 lb tires, I already had them as my winter tires on another car) right after I bought the BRZ and drove with them a few months. Seemed fine.
About a month ago I had a conversation with an auto journalist friend who had talked about the Primacys with a Toyota engineer when the twins came out. During development, Toyobaru did all the endurance and track testing on those tires. The idea was they were choosing the Primacy because it was affordable and capable and fit with the philosophy of the car. Then Michelin cut allotment to the U.S. because hardly any cars are sold with them here. The price shot up ridiculously (they're $3-400 per set in Europe). So I got the stock Primacy's back on the car and it felt alive for really the first time. They're also a 240 treadwear tire (a B'stone S-02 Pole Position is 280.) There's some magic in those "Prius" tires on our cars, man. :D

More grip = more roll. :)

- Andrew

The oversized tire may be contributing to the feeling of instability as well, go back to the 215 with the 7" wheel next time. The first shop I called for tires suggested I stay with OE size and I'm glad they did. You're not the first person to be unhappy with 225/45/17 MPSS on this car with the 17x7 wheels.

If you're not chasing a lap time within a ruleset there's no reason to mismatch tire and wheel sizes.

Thanks everyone for the info. I will try to go back to stock size next time around. Are the mpss superior to the primacy for handling or in any department or are they completely different animals?
I just read so much good things about the mpss that I was expecting more. So far I feel it is stickier though.

The MPSS is significantly stickier than the stock primacies, they'll also stand up to track use without chunking a lot better.

I don't think it's an oversimplification to say you've bought a decent set of track tires that do not work well on our car on the street. Only briefly even with "spirited" street driving are you approaching the loads and demands on a tire used on track. Mostly what you get with a PSS on the street is the ability for your friends to see you've really gotten into this whole car thing. I'm making this judgment because I've done exactly the same thing before.

I wouldn't call the MPSS track tires, but it is true the OEM suspension is not designed for them. They're good summer street tires with some decent grip. The OEM tires do not have much grip.

It's always important to build your suspension to match your tire choice.

- Andrew

Right, I agree, it's not an R compound tire so it can't be a "true" track tire. But a lot of people choose it for double duty nonetheless. Andrew, what's your choice for a 225/45-17 track-oriented tire on a BRZ with camber plates as the only suspension mod?

I changed to 225's a little while back and now my car handles like shit

^^ On track??

No just on the street. They aren't great tires (riken raptor HR), but i feel a lot of sidewall flex that I doubt would be there if they were 215's.