[douglas751]

This question is for those who track their 968's (DE) and enjoy doing so.



I have a 968 with 17" wheels and Pilot Sport 2 for the street. For the track, should I use these tires and tear them up, or buy a set of 16" Pilot Sport Cups for the track? I already have the 16" OEM rims, and also have too many other sets of wheels and tires in garage from my 911, so I am not going to run out and buy another set of 17" rims. I already know who well the Pilot Sport Cups work since I have them on my 911 for DE's, but just wondering if the width difference of going down to 16" will lessen the benefit of going with the Pilot Sport Cup tires enough to make this not worth my time.



BTW, the car feels quicker with the 16", I suspect the reason is the reduced weight.



Thank you!



-Doug

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[flash]

every car reacts differently with different tire and wheel combinations - what happens on a 911 won't be the same thing that happens on a 968 - weight distribution, braking and intitial set are completely different



as for which way to go, that depends on a few things



what kind of track are you running? a high speed track would be better served by the wider rim and tire - a tight technical track might benefit from smaller stuff, just like autocross would



i am not a fan of different size wheels for different purposes, if you are driving the same car on street as you are on track - you spend all week driving the car one way, and then change everything for track and spend too much time getting used to the different setup - consistency is everything when trying to reduce lap times



if you are stuck on doing something like that, then always go with the better grip for track, not the other way around



your cheapest way out is to just keep buying tires - this also give you the best shot at maintaining a feel

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[Lemming]

My .02. I'd use the 16's for a number of reasons.



1. They're cheaper.



2. Just when the track tires are getting good, you would likely want to remove them for running on the street due to limited tread depth.



3. The 17's can be used for your "rain" tire at the track (limited wear at that point).



4. Decreased unsprung weight.



5. Your 17's provide you with a good tire to get to and from the track (I'm assuming you don't have a trailer and tow vehicle).

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[douglas751]

[quote name='Lemming' date='Apr 25 2006, 01:27 PM']My .02.  I'd use the 16's for a number of reasons.



1.  They're cheaper.



2.  Just when the track tires are getting good, you would likely want to remove them for running on the street due to limited tread depth.



3.  The 17's can be used for your "rain" tire at the track (limited wear at that point).



4.  Decreased unsprung weight.



5.  Your 17's provide you with a good tire to get to and from the track (I'm assuming you don't have a trailer and tow vehicle).

[right][post="19773"]<{POST_SNAPBACK}>[/post][/right][/quote]

Does anybody have a roof rack that would fit the 968 and be suitable for carrying tires? I would make something if anybody had just the bars and wanted to sell them.



Thank you!

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[flash]

are these DE events or races? - if it's just DE stuff, i would seriously run the same thing for both - if it's racing, i would still run the same wheels, but track tires for track, and set the wheel size dependent on the type of track



the acceleration, braking and suspension action is so differently when you change things up, that it can be very frustrating as you try to adapt to the change



as an example, with the MGBs, for a long time, we would run 13s on autocross stuff, 14s on tight tracks and 15s on big road race courses, but it was always a struggle getting used to the change - it was easy to find yourself misjudging braking didstance, and gear selection - eventually we stopped doing that, and almost immediately lap times dropped - the time i spent in the car on the street was having a big effect on my technique and timing



think about it - competitive racers spend a lot of time getting used to minor changes in setup - you would be making a major one and just jumping right into the car



keep in mind, on the roof rack, that you have a maximum load of 165 lbs up there - this won't be enough for all 4, so some will have to live inside

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[ether_joe]

[quote name='douglas751' date='Apr 25 2006, 10:31 AM']Does anybody have a roof rack that would fit the 968 and be suitable for carrying tires?  I would make something if anybody had just the bars and wanted to sell them.



Thank you![/quote]



buddy of mine has a Yakima roof rack on his ride he uses for his semi slick track tires. So it can be done.

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[flash]

all 4? if so, that's a good 200#



the owner's manual limits roof load to 75kg or 165# - i have no idea, and it doesn't say, if it was the rack limit or the roof itself, but as soft as the sheet metal is, i'd hate to see kinks from overloading

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[Lemming]

[quote name='douglas751' date='Apr 25 2006, 12:31 PM']Does anybody have a roof rack that would fit the 968 and be suitable for carrying tires?  I would make something if anybody had just the bars and wanted to sell them.



Thank you!

[right][post="19774"]<{POST_SNAPBACK}>[/post][/right][/quote]



A small tire trailer might be your best bet. You can also get 4 16's in the car, just put down a tarp first.

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[Lemming]

[quote name='flash' date='Apr 25 2006, 12:47 PM']think about it - competitive racers spend a lot of time getting used to minor changes in setup - you would be making a major one and just jumping right into the car[/quote]



I don't know of any competive racers who drive the same car on the street as well as the track. Oh wait, I saw Shumi in his F1 car on mainstreet the other day <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" />

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[GuardsRedCoupe]

[quote name='douglas751' date='Apr 25 2006, 01:31 PM']Does anybody have a roof rack that would fit the 968 and be suitable for carrying tires?  I would make something if anybody had just the bars and wanted to sell them.



Thank you!

[right][post="19774"]<{POST_SNAPBACK}>[/post][/right][/quote]





Here's the story on roof racks. There was a factory rack, but it's very hard to find these days. (Ask me how I know)



A Thule rack can be mounted to a 968 with fitkit 170, and can be mounted to a 944 with fitkit 034. These fitkits can be hard to find, however.



Another (more readily) option is a Saris rack (90" load bars are just long enough) with 010 brackets for the front and the rear. Unlike the Thule, Saris continues to produce the required brackets. Saris' accessories are more limited than Thule or Yakima.



As ether_joe meantioned, Yakima also has a rack that fits, but I didn't get around to looking into their options.



Like Flash, I'd be cautious about the weight, but I know it has been done before:



[center][/center]





As Lemming said, a more practical option would probably be a trailer: method one / method two



[center][/center]

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[flash]

oof - yeah - real careful on the weight - i'd find out why they limited it to 165# before trying that one - maybe he's done it, and just hasn't hit the right (or wrong) bump yet



lemming - i know plenty of competitive guys who drove their car both on street and on track - scca thing that happens a lot in the street prepared classes - something else that is pretty common is to have 2 nearly identical cars - one for street and one for track - i did this for years - the only differences between them were tire compounds, catch bottles, and fire systems



really makes for a great practice session every time you take out the car - we all know that seat time is wht makes lap times go down - why not get as much as you can in the same car, or at least close to it?



given a mandated choice, i'd make the compromise on the street setup - not on the track setup

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[Clem]

I don't think there is a huge difference. If you are comfortable with the MPSCs then go for it.



Plus, the less rubber on the 16s will probably come up to temp faster and be easier to manage.

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[flash]

tread width is over an inch less each (that's about 12%) and sidewall flex is dramatically more - there will be a big difference in handling



tire temps probably will come up faster, and then go higher - that will likely hurt high speed turn stability



in an autocross though, everything is different, and that can work to your advantage



so, again, the real question is what kind of track?

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[bob blackwell]

I had an opportunity to compare my times at the 2004 Porsche Parade using my street 16 inch wheels and Michelin Pilot Sport tires and then changing to 17 inch 968 optional wheels with Michelin Pilot Sport Cup tires mounted. I lowered my time by five seconds using the larger wheels and sticky tires. (not exactly the answer to your question, but maybe it will help you reach a decision). My personal best times have been accomplished at the local race track using 18 inch wheels and Hoosier R3S04 competition tires. In my experience you can't beat more rubber on the ground and the softer the compound the faster the lap times. Of course they are more expensive and don't last as long. Good luck, Bob Blackwell.

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[Dave]

You can never have too much rubber.

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[Straight Four]

just my .02 but the reason your buddy can do all four is that even though the manual says 75kg... they are using what we engineers call a safety factor... really its probably more around 100kg... (not recomended but is possible but i wouldnt try on sucha beautiful car...)



we add in a fudge factor so that the bars will most def last for a while if you carried a certain weight on them... the factor can be as high as 10 or as in airplanes as low as .5 (weight makes a big factor in reducing this safety one).

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