marlinspike

So, it's not for a Porsche, but it seems the Porsche forums are the only ones where a person can get an informed opinion on matters of handling.

Right now the car has 245/50-16 Michelin Pilot Sport A/S tires on it. Now that I've moved a bit further south I'm willing to go to summer tires. Also, the sidewalls on these Michelins give too much on the front tires (i'm wearing out the edges on the front tires, more pressure and I won't but that takes so much pressure the centers wear out. I'm thinking about going to 245/45-16 on the next set of tires (don't worry about the speedo, it's close enough to either size, reads low for 245/50 and high for 245/45). As it is the car exhibits slight understeer, but is pretty close to balanced.

So, I'm open to suggestions but I think I've narrowed it down to:

Goodyear Eagle F1-GSD3
Fuzion ZRi (this one would allow me to do 245/45-16)
Firestone Firehawk Wide Oval
Bridgestone RE960AS
Yoko ES100 (would allow me to do 245/45-16 in the rear and 225/45-16 in the front)

I like the idea of going to 245/45 to give me a little more acceleration and a little less sidewall wiggle, but only the Yoko and the Fuzion come in that size. I'm also toying with the idea of doing 245/XX in the rear and 225/XX in the front to reduce rolling resistance. I figure the smaller diameter of the front tire would make up for the understeer introduced by going narrower up front.

Thoughts on any of this?

sjfehr

I was googling and data-mining numbers (mostly from Tirerack), and tried to compile a cross-comparison to help try to quantify what the hottest tire this year is, instead of just relying on anecdotal evidence since everyone seems to always love whatever they get; I posted it to autocross.us a few weeks ago, but it's just as relevant here and might help you decide. These are all the highest-end summer tires I could find:

Tirerack testing:


Looking strictly at Tirerack's dry track scores (225/45R17 on a 2008 BMW E90 325i Coupe for the first set of 4 (above), and a 2006 for the others):
8.67 Dunlop Direzza Sport Z1
8.64 Yokohama ADVAN Neova AD07
8.64 Dunlop Direzza Sport Z1 Star Spec
8.58 BFGoodrich g-Force T/A KD
8.39 Kumho Ecsta MX Extreme Performance Summer
8.30 Goodyear Eagle F1 Asymmetric
8.26 Bridgestone Potenza RE-01R
8.24 Sumitomo HTR Z III
8.23 Michelin Pilot Sport PS2
8.20 Bridgestone Potenza RE050A Pole Position
8.15 Continental ContiSportContact 3
7.96 Yokohama ADVAN Sport
7.46 Hankook Ventus R-S2 Z212
7.23 BFGoodrich g-Force Sport



0.98-0.99g BFGoodrich g-Force T/A KD
0.98g (=) Yokohama ADVAN Neova AD07
0.98g (-?) Goodyear Eagle F1 Asymmetric
0.98g (-?) Kumho Ecsta MX Extreme Performance Summer
0.97g (-?) Dunlop Direzza Sport Z1
0.96g (+?) Dunlop Direzza Sport Z1 Star Spec
0.96-0.99g Bridgestone Potenza RE-01R
0.96g (-?) Michelin Pilot Sport PS2
0.95g (+?) Sumitomo HTR Z III
0.95g Hankook Ventus R-S2 Z212
0.94-0.96g Bridgestone Potenza RE050A Pole Position
0.94-0.97g Continental ContiSportContact 3
0.92g (+?) Yokohama ADVAN Sport
0.93g BFGoodrich g-Force Sport

Not reviewed:
Falken AZenis RT-615
Nitto 555 extreme

They unfortunately switched cars between the two sets, and tires they tested twice (even on the same car) scored differently in the two tests, but I'm hoping the overall numbers are at least reasonably comparable for a cross comparison. Given the apparent +/- 0.04g margin of error in Tirerack's testing and the 0.04g spread between 11 of the 12, it's hard to really say any of these tires is a clear winner or loser per Tirerack's testing. [I marked (+/-?) where the other tires in the tests did significantly better or worse in the other test, throwing a bit of doubt on how this particular # should be in comparison with the others.] The Neova's did exactly 0.98g in 3 tests on two different cars, though, so they're at least consistent!

Here are the other charts:
http://www.tirerack.com/tires/tests/...ay.jsp?ttid=93
http://www.tirerack.com/tires/tests/chartD...ay.jsp?ttid=107
http://www.tirerack.com/tires/tests/chartD...ay.jsp?ttid=100
http://www.tirerack.com/tires/tests/...ay.jsp?ttid=71

I found this helpful comparison on the RX-7 club forum from someone who's autocrossed all the top 3 tires. Sadly, not HTR Z III though, which is tantalizingly inexpensive:
And posted to evolution.net:
Hankook's supposed to be rolling out their new tire, the R-S3 Z222, in April. Their press release touts 30% greater dry-grip performance, which is... wow. Doesn't help me much, as my inspection is up in April and there's no way my rear tires will pass. But it may well put Hankook right back on top when it does come out. I'm looking forward to seeing what the reviewers say!

http://www.hankooktireusa.com/press/press_...iew.asp?pid=251

Nitto is coming out with their new NT05 in February:
http://forums.evolutionm.net/motor-sports/...class-tire.html

The new Bridgestone RE-11 will be out in 3-5 weeks, too! Choices, choices, choices...

Edit: I've decided on Star Specs, but I'm waiting until closer to March to order and keeping an eye on the other 3 new tires, too. If I wasn't racing (or cave and get another set of wheels & r-comps), I'd go with the Sumitomo HTR Z III since it seems to be 95% of the performance with way better treadwear for half the price.

marlinspike

Unfortunately, my car uses a bit of a weirdo size (though there are plenty of competition tires in that size). The only tire listed in your post that fits my car is the BFG G-Force Sport, which lost in a head to head against the Fuzion ZRi that also comes in a good size for my car - they're about the same in the dry but the BFG is much worse in the wet. One thing that worries me though is Fuzion talks about sports cars and sport compacts, but my car weighs in at around 3700lbs. EDIT: The RS2 comes in my size too, but that's another tired that isn't so good in the wet.

I'm surprised the Goodyear Eagle F-1 GS-D3 isn't on your list - it won the Car & Driver shootout.

Also, I see you're in Chesapeake. Hello from Williamsburg. Do you have any recommendations for the following:
Tire shop - must have two-piece Mercedes wheel weights (used by BMW as well)
Upholstery shop (to replace the bowed fiberboard that supprts the headliner on my sunroof)

The RS2 Hankook comes in the right size so maybe the RS3 will too.

marlinspike

There's also the Cooper Zeon 2XS in my size. Anybody know anything about it? Same goes for the Kelly Fierce UHP.

I really would like to do 245/45 though, so if it's a multi-way tie, my preference goes to the ES100, Fuzion, or that Hankook you mentioned, as those are all I can find in 245/45-16 that's decent, but I'm willing to do the 245/50 again if it'll handle better.

sjfehr

Your tire IS an odd size, isn't it? From your OP, 245/50 and 245/45 should both work fine; it's only a 12mm height difference between the two and will equate to a 4% difference in speedometer/odometer and a 4% lower gear ratio for the 45 over the 50. Are you racing or just driving for fun? Actually, I only included the g-force sport in there because it's what the prior owner put on my Boxster S and I autocrossed with them all last season and wanted a benchmark for comparison with the fastest street tires out there. There are better tires in that class, but I didn't look all that hard.

You might try http://www.vadriven.com/forums/ to ask about local shops. It seems to have a high % of road-racing teens, but the 757 forum is a busy one and I'm positive someone there can help. (I've just been taking my cars to the big chain tire shop down the road for mounting & alignment, though I may hit All-aspects Motorsports the first new set on my Porsche.)

marlinspike

Yeah, it's a strange size. I think it was a short lived 80's performance size - I saw on here a guy with a 944 Turbo asking about the same size. There are a ton of competition tires in the size, but only a handful of street tires. The car in question here is a 1985 Mercedes 380SE, but with AMG wheels.

I can use 245/50 or 245/45 because the speedo is set for something in between (car came with 205/70-14) - 245/50 is 1.4% too big and 245/45 is 2.4% too small, but both are within the acceptable range. However, if I want to use 245/45 I have 5 choices, 2 of which I think I've ruled out (Yoko AVS ES100, Fuzion ZRi, Hankook RS2, Conti ContiSportContact - yes, ContiSportContact 1 - and Sumitomo HTR z).

Driving for fun mostly, but I may start hitting some autocrosses - I'm not really sure what I'll do with the car because the car left the factory with 155hp (204 in europe) - and while I haven't gotten it on a dyno yet, I'd say it's in the mid-300hp range now (with the 2.47 rear end on it it'll get to 60 in under 6 seconds, and I still haven't had the mixture or timing mapped - mixture is way off now because it's engine vacuum based and I have lumpy cams - and there is a guy with a 2.88 that'll work who is thinking about swapping with me). That's part of the reason I want as good a tire as possible - I like my suspension to be able to keep up with my engine (changed the shocks to Bilstein B6, but left the springs stock as the suspension geometry is designed to use the full travel)

I'm reading nothing but good things about the Coopers, but that doesn't really mean anything.

sjfehr

If you want to autocross, there are four clubs within an hour or so drive from Williamsburg. TSCC races in Norfolk (excellent venue at the Navy's LCAC strip at Little Creek), ODR SCCA races in VA Beach (****ty old WWII airstrip, but they're looking for a new venue) and NASA races mostly at VMP near Richmond, but they have some autocrosses at the Langley Speedway in Hampton and do other sites, too. VMSC is in Richmond, too, but I'm not familiar with them, I think they race at VMP also. The first TSCC autocross at ACU4 is March 15 (all dates are up on the website). NASA and SCCA haven't announced dates yet, but Jon's said there won't be any NASAcross at Langley this year.

http://www.tidewatersportscarclub.com/
http://www.get-fast.net/nasacross/
http://www.odr-scca.org/component/option,c...lpro/Itemid,30/
http://www.vmsc.org/

marlinspike

Cool. I think I should have this car ready to go by March too. It'll be interesting to have the 16.8ft beast barreling down an autocross track.

marlinspike

My friend who used to engineer suspensions for Ford tells me that with the staggered setup I was thinking about the reduced front tire width would substantially increase understeer while the slight change in rake would only barely reduce it, so I guess that kills the staggered idea. Which makes me wonder why BMW runs a staggered setup on the 135, a car that has so much understeer that even though they put a 50lb dead weight in the back bumper it still understeers.

sjfehr

Porsche does the same thing, and it absolutely boggles the mind... They go to such great lengths to design a 50/50 distributed car... then spec out stock wheels and tires and camber that make it plow like a FWD. Guess they figured enthusiasts could easily fix it, and the average spirited driver was less likely to die that way?

marlinspike

Looks like there are also the Toyo T1R and R888 in 245/45. There is also the Dunlop SP Sport 8000 in 245/45, but oddly enough that tire says for a 8.5-10 inch rim, where all the other ones say for an 8 inch rim.