TiresTiresThe Bay Area Probe Owners Club does not endorse or avoid any specific automotive business or product. Use this information and these links at your own risk. Note: Most of this information is collected from the Probe Performance List and should be considered hearsay until YOU verify for YOURSELF. Being listed here does not imply suitability for your application. I may post parts of email messages I receive. If the author objects to this policy, I will re-edit or remove the text to satisfy you.
Thanks to Andy Bettencourt, National Solo II champ a few times, who drove a 2nd gen PGT.
1 degree neg. camber at all 4 wheels...MAX
3/16" toe out TOTAL @ front
1/16" toe out TOTAL @ rear - this is toe out!
With the stock shocks, the car needs to have the rear set to rotate a little. In 1995, I had zero toe in the rear and adjusted the tire pressures as I saw fit to get the rear to 'move'. The car is by no means uncontrollable and in fact, it handles like a car 500lbs lighter. This year I run the rear pressures at what they should be, so the car gets the right amount of tire on the ground while the suspension does the work. 245/45/16 BFG's at 38F, 34R - this may sound high for what some people are running. The reason for the 'Groove of Doom' is underinflation. BFG says these pressures are correct and my seat-of-the-pants tells me the same.
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I've found these pressures to be right for very grippy surfaces, but most of the parking lots here in Rochester are slippery, newly sealed asphalt. Under these conditions, I've lowered pressures to a minimum ~33F, 30R. I keep the rears a little high to help the back end move (I haven't experimented with the alignment changes mentioned above yet). For reasonably grippy surfaces, anywhere between 35 and 38F should be fine. Just watch for wear in the center groove at the lower pressures.
The R1's were $130 each when they carried them at Tire Rack. The g-Force R1's are the replacement, and the major difference, besides the tread pattern, is the g-Force has symmetrical sidewalls, ie. they're both the same stiffness (I read this almost a year ago at the Tire Rack, so it's possible that this isn't true.). The old R1's were asymetrical, with the inside sidewall being stiffer than the outside to provide some negative camber during cornering.
For the road course, I'd probably keep the fronts at 38 and maybe take a couple of pounds out of the rears. Of course, I've never road raced, so I'm talking out of my ass on this. :) The best thing to do is try it, measure the temps across the tire and infate/deflate to achieve consistent temps across the tire.
Toyo Tires, fifth largest tire manufacturer in the world.
Pirelli P7000SS-Exceptional wet weather tire, higher grip than the stock Gatorbacks, very quiet, they wear exceptionally well, and I had a 60ft. time of 2.08 with the Pirellis! Downside, I just think the sidewall is plain ugly, and ultimate dry grip may not be there. They're very neutral with quick turn in and they're stable at high speeds. They change direction easily. Size tested: 225/50R16
Firestone Firehawk SZ50-The cheap brother of the S-02, again great rain qualities, higher dry grip than the Pirellis, very quiet, but will wear faster than the P7000's. As they get worn, they get slick, and their wet weather capabilities diminish. Nice sidewall design with integral rim protector. Stiff sidewalls, but the ride was nice. They deteriorated quite rapidly after the installation of Eibach springs with no accompanying alignment. Otherwise a 35K tire easily. Size tested: 225/50R16
Yokohama A520's-I've been meaning to write the list with a report on these tires for some time. Unfortunately, it hasn't rained here in over a month and I haven't had a chance to test them in the wet as of yet. Dry performace is exceptional and I'm now way over-tired with a 245 section width. My only complaint with these tires is that they're noisy. Sharp steering, good feel, and suprisingly, they're wearing well. They have the lowest treadwear rating of the three tires mentioned, at 180AAA. If I had to purchase one of the three again, it'd be the Yokohamas, albeit with a shorter sidewall! Size tested: 245/45R17
Dunlop D40 M2 - "Max performance" Good replacement. Local "Just Tires" center quoted me $90 for 225/50ZR16 (or $110 for VR. Go figure). Apparently some mail order places had them as cheap as $74, but may be close to out of stock (older tire design). Commonly used by list members.
Dunlop SP8000 - "Max performance" Better replacement. Same tire shop quoted me $100 for 225/50ZR16, no VR. $89 from Discount Tire Direct from June 98 SCC.
Dunlop SP9000 - "Ultra High Performance" $178 from the same Discount Tire Direct.
Yokohama A520 - "Ultra High Performance" A recently introduced tire. 225/50ZR16 for $109 same dealer, same mag.
Pirelli P7000 SuperSport - "Ultra High performance All Season" At least one list member uses them (Kirk P). $126 from same mag. 29Jun98
Dunlop D40M2 - Bought these in the 225/50R16 size as replacement for gatorbacks summer 1996. They are close to worn out 30K later (now Oct98), but I've got half a dozen autocrosses and two road race schools on them. They were rotated and the fronts balanced every 6K. I bought four more from the Tire Rack for $77 each. I have an extra set of rims for race tires so the dunlops provide enough grip for the street. James
Yokomaha AVS Intermediate - Exceptional dry grip, poor in wet in the 245/45R16 size. A friend of mine was considerally slower in his 94PGT at an autocross using these tires than I was in my 94PGT on Dunlop D40 M2's, usually he is faster. Very pleased with performance at Thunderhill Raceway Track Day July 1998. I was able to obtain corner exit speeds as fast or faster than a friend in his 94PGT on 245 size R1's ! I was also able to catch up to and pass a Viper GTS with truly huge tires.
Dunlop D40M2 - One thing I'm noticing about the D40 M2's. If I let the car sit for a week, the tires develop slight flat spots. It takes about half an hour of driving for the vibrating to go away. If I only leave the car for a day, things aren't as bad.
This flat spot effect should only happen in the winter but it's definitely happening to me and it's over 50F outside. www.aracnet.net/~mikey Oct98 (2 reports of this)
The Bay Area Probe Owners Club does not endorse or avoid any specific automotive business or product. Use this information and these links at your own risk. Note: Most of this information is collected from the Probe Performance List and should be considered hearsay until YOU verify for YOURSELF. I may post parts of email messages I receive. If the author objects to this policy, I will re-edit or remove the text to satisfy you.
March 1998
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