J1NX3D

i have staggered rims 7"s and 8"s right now with 205s and 225s. When I eventually change to late offset I'm going to try to avoid some of the trouble sourcing good tires for 16" rims here in NZ by looking for some 17" cup1's.

these rims should be square, yes? is it a good idea to stagger tires on them too or stay square to suit the rims?

If I could keep my fuchs I would have liked to have gone 225's front and 245's rear. If i have to stay square with the 17's I'd go either 225 or 245 all around depending on price.

TIA

ernie9468

Don't know what your driving but but I assume it's a 951 87 +, if so you can go either way staggered or square,what I got on my 968 are CupI 17x8 front with 225-45-ZR 17 tires....rear 17x9.5 with 255-40-ZR 17 tires.Btw it's not only a popular combo for the 968s crowd but also for the 951s.

racer

Most newer Porsche wheels (Cup 1 for instance) are usually found in staggered sizes.. so you would have to take the time to source 4 of one size , or buy two sets of staggered and sell off what you don't need etc).

No real reason to "stay square" unless you want to ease your tire rotating chores.

I run 225 front, 255 rear on my 17" wheels.

MAGK944

Staying square does have two advantages:

1. Easy rotation
2. Less understeer

With a larger rear you are inducing more understeer to a car that already has too much. So think about going one or two sizes up on your on your rear sway to counteract.

J1NX3D

Ah i thought you'd remember my car Ernie! Its a RoW '86 n/a currently wearing 930 fuchs.

thanks guys, food for thought.

I'm hoping, but it might be a long wait, that i can find some 968 17's.

944hal

Going square can induce less understeer or conversely, more oversteer. Square has the advantage of being able to rotate your tires. If you have adjustable sway bars you can compensate. My first experience on the track with 16/245's square was scary. Too much oversteer. I have an adjustable rear sway so I was able to dial in the handling. I like a square set up because on track the front tires take more abuse and I'm able to rotate them to even out their life. I've run 245's on 16 rims square and 255's on 17 rims square. With the adjustable rear sway bar I can dial in the handling to suit the track.

thirdgenbird

944 and 924 guys just need to team up. ive got two sets of wheels for my 924s and they all consist of fronts. somewhere out there someone is running all rears.

chrisc

[QUOTE=944hal;9262907] My first experience on the track with 16/245's square was scary.

That's cuz you finally figured out what the gas pedal is for!

bad_monkey

I'm running staggered BBS RS, 9's and 10's - but more for looks than anything else

Try www.adenstyres.co.nz for a good deal on 16" tyres in NZ. I bought Toyo 225's and Hankook 245's for the above.

Cyberpunky

My car came squared but I had it back to staggered within days. It just didn't look right (to me) and needed new tyres, so had to make a choice very quickly. I think unless you are racing the car, having a little understeer is safer(Porsche got it right IMO), and you can't really say that a little understeer makes these cars handle poorly. Personally I love how my car handles with the staggered set up, but my car is only street driven
peace
Cyberpunky

MAGK944

You are right, slight understeer is safer than oversteer on a street car, neutral is however safer still Going staggered simply adds to the stock understeer so you are going the wrong way. Best to dial it back a bit with a larger rear sway or just up the tire pressures on your front tires to compensate.

" ...I love how my car handles..."

Ultimately this is all that really matters, if it works for your driving style then stick with it.

ian

Larger rear sway bar = decreased understeer
Upping front tire pressure = increased understeer

MAGK944

Fixed it for you.

You need more rear sway not less to correct understeer.

From Clarks:

ian

Mike,

I will hold by my statement, increasing tire pressure up front will lower grip (assuming your tires were properly inflated to begin with). Clark's Garage is a great website, but try the SCCA or NASA sites to get better info on tire pressures.

There is a simple way to test this, albeit using the other end of the car. Next time you go to an auto-x have you rear tire pressure at the factory psi, do a run, add 5 psi, do another run, add 5 more psi, do another run. The back end of your car will get looser and looser as the tire pressures come up.

MAGK944

Yep, I sort of guessed what you were trying to say there, however the factory square set-up still exibits understeer so removing the rear sway won't help.

Real world experience is a better judge. To tell you the truth I could never understand how increasing the front or decreasing the rear tire pressure would correct understeer. Yet all the books I read on suspension dynamics and on other sites (tire-rack below) stated the same. Maybe some expert would chirp in and explain. Maybe it's something to do with slip angle as you turn?