Why are the stock F1's useless? You mean they are wore out or they cant handle the power? Its not like 400rwhp is some amazing number that needs some special tires. On my 400+ rwhp Supra I had Cooper Zeon's, and they held traction all the time except for 1st and 2nd gear when the boost hit. Plus they were only 275/40/17's. I think 295 18's F1's should be ok.
The OEM Goodyear's have asymmetric threads with the outside being very blocky with little channels to squeeze out water. The outisde othe tires tend to hydroplane a littles and are not acceptable to me for street tires which have to live with rain. I am on my second set of Kumho Ecsta MX tires which I think grip as well the Goodyear's, have symmetric treads whih do great in water and are alot less expensive than most other tires. Kumho's :thumb:
Sounds like you are looking for a sticky tire, no ? Nitto R2s are the only game in town...
How long Nitto R2's will last depends on how you are using them. If you are driving your car on the street, I would say 10-12,000 miles is a safe bet. My first set lasted me about that long with a Mag and pretty agressive driving. If you are at the track doing full burnouts every weekend, it's gonna be much less. Nittos are a very soft compound, that's why they solve traction problems with a high hp car. Forget about it, they are a road race tire and will stick your car to the road so much better than F1s, you'll never buy F1s again.
If you have Mods and want a street tire that can deal with 'em, Nitto R2s are your tire. Stock Z06's are traction challenged already, if you add more power it only gets worse. F1's on my car are basically ice skates.
The only power that matters on the street is the power you can use. R2s stick way better than F1s and the more power you have, the more you'll need 'em. Nitto R2s are the best street tire for an enhanced Z IMO, and drivable in the rain by the way.