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Old 11-20-2017, 02:52 PM   #41
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Forgot to ask, what tire pressures are we talking about if going squared? Maybe i try put my existing 255 AS/3 up front and install new RA1 in the back for starters. Existing as/3 are fairly new and i live in portland OR, so im trying to have wet weather capability..back to pressures....What would be reccomeded?
Im thinking as/3 fronts would offset the grip with RA1 in the back. Am i tottaly wrong here?
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Old 11-20-2017, 02:57 PM   #42
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Forgot to ask, what tire pressures are we talking about if going squared? Maybe i try put my existing 255 AS/3 up front and install new RA1 in the back for starters. Existing as/3 are fairly new and i live in portland OR, so im trying to have wet weather capability..back to pressures....What would be reccomeded?
Im thinking as/3 fronts would offset the grip with RA1 in the back. Am i tottaly wrong here?
Thanks
Completely incompatible tires. Your car would push like a pig all day.

Maybe choose some middle ground and mount RE71R on all 4 corners. This is a fast tire that works street or track. Almost as fast as RA-1 but works better on stock suspension. You will still toast the outer shoulders but a better fit than RA-1 tires.
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Old 11-20-2017, 03:02 PM   #43
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What is the easiest way to adjust camber? Are gt3 arms required or is there a cheaper way while running stock suspentions? Maybe ill be better off just running staggered and get better tires? Hmm but still a camber adjustment is a requirement i understand, if i am to track it at all right?
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Old 11-20-2017, 03:23 PM   #44
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What is the easiest way to adjust camber? Are gt3 arms required or is there a cheaper way while running stock suspentions? Maybe ill be better off just running staggered and get better tires? Hmm but still a camber adjustment is a requirement i understand, if i am to track it at all right?
Lots of guys do lots of things to get camber in the car. Slotted strut mounts, camber plates, coil overs, lowering springs etc. All can work to some degree and there are a dozen threads here pontificating the merits of each. The top Porsche setup shops all over the country pretty much agree: "Just get GT3 adjustable arms." They make the setup and alignment process very straightforward and they will transform your car into a track worthy machine.
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Old 11-20-2017, 03:54 PM   #45
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Youre advice and recomendations much welcome. Thank you!
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Old 11-20-2017, 05:17 PM   #46
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Could you tell me what the offsets are for those rims?
Probably ET55
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Old 11-20-2017, 08:48 PM   #47
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Im thinking as/3 fronts would offset the grip with RA1 in the back. Am i tottaly wrong here?
Trying to balance the handling with different front and rear tire compounds is the wrong way to go about it. Well, that is unless you have a large selection of tires to choose from and have time to do a lot of testing (which I am assuming you don't).

Here is the standard process to set up a car with one set of tires: Install the same tires on the front and the rear, THEN use the suspension to adjust the handling, THEN use tire pressures to fine tune the handling. And don't forget, the driver may need to adjust their driving technique to get the most out of any given setup.

In this case, the problem is that the stock suspension has no adjustability. The Porsche factory gets around this by doing tons of testing to find the right mix of tires (type and sizes), suspension, and tire pressures that result in the handling that they want. Without adjustable suspension and with only one type/size of tire, you don't have anything left to use for adjustment (except pressure which is not going to move the needle very far).

I've done lots of laps on RA-1's; shaved vs full-tread, heat-cycled vs non-heat cycled, in the dry and in the wet, but I've never mixed them with an all-season street tire.

Best of luck.
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Old 11-20-2017, 08:58 PM   #48
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Seeing that photo of Boxster on three wheels got me waay exited.
I think that you mean like this? The photo earlier in this thread shows a Boxster on TWO wheels (most likely after hitting the curbing and bouncing both inside wheels into the air).

It takes the full Spec suspension to get the car to handle like this. And look at the right front, the tire is nice and flat to the track while the wheel is at roughly zero camber (when fully loaded). It needed -3.7 deg camber (static) to be able to achieve that and the only way to get that kind of camber is adj lower control arms.
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Old 11-20-2017, 09:25 PM   #49
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Cool

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Originally Posted by Brad Roberts View Post
Testing 245 A6 square for 2 lap time trial format blast. It worked

This is the photo, this forum page two.
So my new to me rear wheels which soon to be on the fronts are in their way to me. A nice felow from ebay traded me them for many dollars.
To start with camber adjustment to make even tire wear, lower controll arms would be the first mod. Are we talking about just the fronts or all the way around? I plan to gradually get to the rest of the suspension, in stages. I read spec boxster allows stock suspension...i cant believe anyone would be much competitive when other guys going balls out and doing the whole new everything suspension wise..


Please excuse the thread ho jacking.
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Old 11-21-2017, 04:25 AM   #50
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I have yet to install GT3 LCAs on the rear, but did install new 986 LCA's and the tarrett rear toe control arm.
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Old 11-21-2017, 04:57 AM   #51
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Typically you can get plenty of camber on the rear, especially if there is any lowering at all. I am at -1.9 and I am at OEM USA ride height. In fact when you get some lowering, often the camber is excessive and can't be dialed down without adjustable toe links. Another considering in using GT3 LCA shim type arms in the rear is you don't want to mess up the axle geometry, I think that is why some folks have trouble getting enough front negative camber on turbos and C4s, and there are axle spacers from Porsche that help to resolve this.
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Old 12-05-2018, 03:17 PM   #52
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I'm apologizing in advance if the answer to my question is in here somewhere and I missed it.
I own a Boxster which is a street car and run factory original wheels and tire sizes. I have 2 C5 Vettes, a Z06 for track and conv for street. I have 2 Miata's. Spec set up for track and 1 for street. I run 4 square set ups on all 4 cars. Essentially same tires and wheels except in winter when I go to an all weather tire for the street cars. The 4 square set up simplifies things for me. Rotating tires, moving tires and wheels between cars etc.

I do between 30-40 DE (no autox) track days per season. I run in instructor and advanced groups. My days of of running for times are long gone. I'm out there purely for fun. I'm in the process of negotiating a buy on a '09 Cayman S. The plan for this car is to keep it completely stock, any modifications will be minor and only for better/safer performance such as maybe brakes if necessary. Otherwise, no racing seats, no roll bars, no harnesses no nothing. Keep it as street as possible and will be driving to and from tracks.

My question that I did not see answered here are what would be the best size tire to run on all corners. I did see 255's mentioned for rears but not on all corners. If it makes sense I'd prefer a 17" wheel but would go to 18", would definitely not go to a 19" wheel. On my Vette I use spacers on front but only for wheels to clear bigger calipers. I had a v8 Miata and ran 4 square with spacers on all corners to clear bigger calipers.
Summing up:
What size wheels would work best?
What size tires on all 4 corners would work best and does it make sense to go wider then 255's?
I think that's about it.
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Old 12-05-2018, 06:10 PM   #53
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In Cayman sizes (roughly 25.5-.6" diameter) there are hardly any tires that fit on the Cayman 17" wheels, 245/45/17 is one and 275/40/17 but the 275 is too wide for the oem wheel and barely anybody makes wider 17" wheels for Porsche fitments unless they are $$$. However plenty of good 18" wheels and lots of tires in those diameters. You could run 225/45/17 and 245/45/17?

On 986 Boxsters i have seen 255/40/17 square and I think 225/45/17 square on Hoosiers or hankook z214
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Old 12-06-2018, 05:29 AM   #54
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Originally Posted by steved0x View Post
In Cayman sizes (roughly 25.5-.6" diameter) there are hardly any tires that fit on the Cayman 17" wheels, 245/45/17 is one and 275/40/17 but the 275 is too wide for the oem wheel and barely anybody makes wider 17" wheels for Porsche fitments unless they are $$$. However plenty of good 18" wheels and lots of tires in those diameters. You could run 225/45/17 and 245/45/17?

On 986 Boxsters i have seen 255/40/17 square and I think 225/45/17 square on Hoosiers or hankook z214
on stock 986 17's, you can easily run 255/40-17 rear and 225/45-17 front
those sizes are virtually the same diameter and lot sof tire choices in those sizes
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Old 12-06-2018, 07:31 AM   #55
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Originally Posted by steved0x View Post
In Cayman sizes (roughly 25.5-.6" diameter) there are hardly any tires that fit on the Cayman 17" wheels, 245/45/17 is one and 275/40/17 but the 275 is too wide for the oem wheel and barely anybody makes wider 17" wheels for Porsche fitments unless they are $$$. However plenty of good 18" wheels and lots of tires in those diameters. You could run 225/45/17 and 245/45/17?

On 986 Boxsters i have seen 255/40/17 square and I think 225/45/17 square on Hoosiers or hankook z214
Steved0x
Thanks for responding. Going with 18" wheels is no problem. I'd like to get as much tread to the ground that makes sense: It looks like from what I see posted that 255's work. Will a wider tread work/fit or is that sort of a diminishing return by possibly adding too much weight & resistance.
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Old 12-06-2018, 08:21 AM   #56
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on stock 986 17's, you can easily run 255/40-17 rear and 225/45-17 front
those sizes are virtually the same diameter and lot sof tire choices in those sizes
I did see a Cayman at Roebling one time running 17" Boxster wheels with our sizes and it seemed to work for him. I guess 1/2" isn't that much of a difference, and it didn't look to bad either
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Old 12-06-2018, 10:13 PM   #57
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I did see a Cayman at Roebling one time running 17" Boxster wheels with our sizes and it seemed to work for him. I guess 1/2" isn't that much of a difference, and it didn't look to bad either
My offer on the '09 Cayman was accepted. It's in Fl and I'm in NJ.
I've decided to fly there and drive the car back to NJ. Turns out it's got stock tire set up on 19" wheels not the 18's I thought. 235x35x19/265x35x19. These are worn summer tires. I'll be ordering tires from TR have them delivered to Fl and mounted before I get there. I've been searching around some other forums and as a result decided to skip the 4 square set up for the street tires. It's too much of a hassle trying to figure out what tires will fit where and on what rims. I've got a short window before heading to Fl to pick up the car, so simplest thing to do is go with what the Porsche engineers decided works best on the car.
Still have a few months before track season starts in the NE and that will give me time to investigate track tire set ups.
Thanks for chiming in.
Next time you hear from me I'll be the proud owner of a Cayman S and a Boxster.


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