Tried some new G-Forces on Beth's RX7 yesterday. They are 245/45/16 and were
heat cycled by Tire Rack. Here are some general impressions:
1. The tire is 1/2" or so wider (cool) and a bit taller 1/4" (damn). Seems a
bit heavier even considering it being a larger tire overall.
2. I used to run hot temps about 30 psi/front and 27 psi/rear on the old R1s.
Camber is 1.9-2 degrees front and 1.6-1.7 rear. Tire temps would be a few
degrees hotter on the inside, with even distribution. Tires would cord on the
inside. Maybe a bit to much camber but didn't want to mess with the setup as
we were used to the handling and better not to change to much midseason.
Ended up running (with same car setup) 44 psi front and 41 psi rear with the
G-forces. Tire temps were even in back and slightly 1-2 degrees hotter on the
outer shoulder on the front.
3. Turn in felt somewhat slower...but this may be because grip is quite a bit
better. This was noticed most in slaloms. You can work the car more
aggressively though. The car (which is inherently tail happy) felt very
stable. Slip angle is definitely higher but less than the Hoosier (ride
experience only). I was able to add a whole turn more rear rebound damping
without producing rear instability.
4. Tires are probably up to 3/4-1 second faster on a 60 second course...this
is using comparison with drivers in our area and back to back testing would be
more accurate.
Definitely a greatly improved tire for a high horsepower rear drive car. Wish
it came with 4/32 tread depth. I don't however see any evidence that this
tire will wear out as prematurely as has been alluded to, at least on our car.
Local RX7 driver that corded his first set believes longevity is equal.
Erik Strelnieks
SS 93 RX7
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