RobbyZ

Hi All, currently I am running 275 18" upfront and 315 19" in the rear on my C6 Z51. Is anyone running a square setup? I use Hoosier R7's and I am hoping they will last a little longer if I can rotate them by going to the same size all the way around. Is anyone doing this? What are the disadvantages? Understeer or oversteer? Can I fit 315 on the front? Anything else I should consider?

JerryTX

Square is great for rotating and traction, but on a narrow body C6 if it is lowered your max width will be 305 square and even then you will have a lot of rub in the pits and some on track over big bumps.. Lots of rub. 295 is a lot more reasonable in the front.

RobbyZ

Thanks for the response Jerry. I did lower the car recently when I put LG coilovers. Im thinking I might got 295 all the way around. Do you run 295/ 30 -18's? I have to see what size hoosier offers.

JerryTX

I have the LG G2 coilovers as well (love them!) and run 305/645/18 Pirelli slicks and my inner fenders are worn through as a result. Its a lot of tire but I love the front end grip. When I go to Hohos it will be 295's yes but I've read the new R7/A7's run wider then previous generations so they may be just as wide as the 305s I currently run. If the threat of rubbing scares you step down to 285 Hohos.

StreetSpeed

I run 295 A7s up front and have no problems with rubbing. Really would like to stick a 315 up there though!

QKSLVRZ

Plus, if the car is balanced with smaller front tires, adding bigger fronts will increase oversteer.

rigit

for the track I run 315 square on my C5Z06 on OEM rears 18x10.5. and I run a bigger front sway bar to help offset the extra oversteer. works great. id imagine it should work great on a C6 too.

el es tu

Is it me or does that tire pressure advice look like what youre supposed to do in the rain - not the dry unless the tires sidewalls were rolling over.


In dry lowering pressure increases the contact patch to gain grip; In wet raising pressure increases the water evacuation of the contact patch to gain grip

QKSLVRZ

I think it applies to the dry as well. You (I presume) still need to have enough pressure to control how much it rolls over the edge, and as you add pressure from there, you'll add oversteer as you lose more and more traction. But you still have to have enough air to hold the tire up on the tread.

STANG KILLA SS

has anyone run into ABS issues with the square setup

AND0

I think you're right, that's the old street tire pressure for edge roll advice, not the newer tire pressure for spring rate.
But from 1986? Wasn't everybody running BFG T/A Radials??

j/k I know they had Gatorbacks, and I remember my Dad got some of those newfangled Yokohama A008s for his 911. That was the hot tire for a while

RHEACERDAVE

LOL I was autocrossing back then and, yes, the A008s were magic compared to bias tires everyone else had.
I don't think physics has changed over the years, though.
Stiff end tends to continue in a straight line.

QKSLVRZ

They were all radials, I had gatorbacks on my shelby charger, and proxes on my stealth.
Maybe the sidewalls were more flexible back then. I do remember people running Hoosers ran in the low 20's for psi.

quick35th

Would you run this setup on the street? I'm looking at possibly picking up a set of ccw classics in 17x11 and running a square setup on them. Was looking at 315/35/17. I just don't know if they'd rub anywhere. These would be going my c5z.

Shane

WNeal

I ran 315s all the way around on my fully converted C6 for a few years and the car did great with it.
I did have to do some cutting in the front wheel wells but by that time, the entire car was gutted out anyway.
Worked for me

RobbyZ

Thanks for all the advice guys. I am finally getting around to buying new tires, but I want to reuse my front 18x9.5 with 56 offset wheels and a 295 tire. That way i dont have to rebuy another 2 wheels to go square. Is that too much of a stretch? Anyone else running R7's 295's on a 9.5" wheel? I need to double check to make sure Hoosier offers 295's in 18".