ExMB

Your's are at one offset and mine are another. You sounded like that is what Forgeline does automatically and did not acknowledge that they do custom offsets as admitted by your answer post and your BGB reference.

Bill Lehman

I was aware of the tread width difference when I specced the 235 to start with. I'm trying the 265 to find out if it works better. Most running Hoosiers are using the 265. The 235 on OZ was O.K., Of those reporting lap times on this board, I'm quickest at WGI. I found my 235 setup had more push then I like at NJMP and changed my swaybar setting from full hard both ends to middle in the F. I'm leaving the setup unchanged for my next outing at Summit Point but will probably change back for WGI.

Yargk

Keep us updated.

Some of the quickest drivers in street GT4s were not quicker with 265s. Seems like if push is an issue, negating push should bring measurable improvements against a stopwatch (even if it's only 0.2-3 seconds), but I haven't seen it reported. Two things I keep thinking about,
1. the stock tires fit the wheel wells and aero is a big deal. If more air gets in the wheel wells, it could negate any mechanical grip advantage. CJ mentioned aero and tire diameter being an issue in the clubsport.
2. It seemed popular to reduce the rear wheels to 10.5 inches when increasing the front to 9. I'd prefer just to add front grip, not subtract rear grip, to get better balance. The real problem is that now two variables have changed so it's hard to see the effect of just increasing front grip.

In summary, more data is better, happy motoring.

jmartpr

I think I read during the GT4 launch that Non-PCCB cars had slight more downforce due to better airflow, not sure on this....if this is true then the car is very sensitive to airflow around the front/wheel well.

Yargk

Yup, sport auto result. Seems with the smaller diameter discs, more air from the brake ducts gets out, just guessing.

jmartpr

That would be my guess too......

Bill Lehman

I mounted up a set of Hoosier P265/35ZR19 F and P295/30ZR19 R and did a trail fit again. Everything fit and no rubbing. A did a few laps at full steering lock both directions on my Cul-De-Sec and then ran a short time on the street. I am at stock ride height and I'm running 2.8 F and -2.4 R camber. The offsets look optimized. One thing I noticed is that the CCW wheels are a very snug fit on the hub. I think once the paint rubs off they will be fine. I'm going to run my old wheels and tires for most of my next event but do plan to heat cycle this set and will report back then.

kfmcmahon

Hey Bill can you post a picture of the car with your old wheel/tire combo below the picture of the new wheel/tire combo please?

How do the tops of the calipers look with the tire clag from the old wheels caught between barrel and caliper?
If you are selling your old set up PM me

Bill Lehman

There was rubber smeared on the calipers but it cleaned off with a little elbow grease. Here's some pics of the OZ set-up. Fronts were P235/35ZR19.

Beantown Kman

Sorry to be the bearer of bad news but if you're going to use Hoosier R7's you'll want more negative front camber. Without running at least -3.0 you won't be using the tire to its full advantage. But if you're driving the car on the street that will create wear problems. You really have to choose your poison. Without more negative camber the Hoosier advantage will be diminished. Even more so as you begin to push the car harder/faster.

Bill Lehman

I know the camber is compromised with street use in mind. I'm considering lowering front ride height for track days to add back the rake lost with this Hoosier setup and that would add a little more negative camber.

kfmcmahon

yes, but you also had Hoosiers on the OZ rims, and if I recall, you lowered your lap times at WGI (and other tracks?), so you got SOME/MOST of the benefit of running a "R compound" semi-slick tire, but maybe not ALL of the benefit of -3.0F/R camber, which may also make it unsuitable for DD.


I found running R7's on my GT3 with stock camber, my lap times dropped by 4 seconds a lap from 2:09 to 2:05 with tires alone .....they actually heat cycled out (25 cycles) before they corded, but of course, the last few laps were sketchy, but a ton of fun, sliding those R7's around....kind of a Chris Harris session

Bill Lehman

Just updating this thread. I ran a session at Summit Point with the CCW/Hoosier setup and just pulled the wheels and looked for issues. None found. I did slightly bend the wiring bracket subject of the 19" wheel warning during trial fit.

Bill Lehman

I just got back from Watkins Glen where I have a lot of seat time and data. I was significantly quicker with the 265 Front compared with the 235. Setup was identical except I softened the front bar from full stiff to medium. I'm also getting more comfortable with the GT4 compared with my old 987. I'm new to running Hoosiers and starting to figure out what they like on my car. Will be posting in the "Fastest Lap" topic soon.

MarcD147

are you telling me I need to schedule a new trip tot he Glenn? looking forward to your update