Tracks in this study:Watkins Glen long course, Summit point main course.
Tires 245 40 18 Hankook ventus, 285 35 19 R888R.
Best lap WGI: 2:16 on Hankook 2:19 on R888R.
Best lap at Summit:1:26 on Hankook, 1:28 on R888R
Camber is -1.9, suspension is Roush 427R shocks and springs.
Laptimes are duplicated in several sessions at both tracks. Laps timed by TrackAddict.
So, this is on your "2007 base (Mustang, with a) 2013 5.0 TiCVT, Magnum XL, 3.73s 393RWTQ/404RWHP", correct?
Of course I'm going to say 245mm tires are too small, but Hankook is SO much better than Toyo R888R I'm not surprised they are faster. Toyo and Nitto are JUUUUUUUUNK. Nobody serious uses these for time trial for a reason. I'd take small Hankook Ventus every time.
Your front camber is definitely lacking at only -1.9 deg. Shoot for -2.5 to -3.0 deg, even with that tiny 245mm tire.
I looked up some comparable lap times, to see where you are at. TrackAddict and any phone app timer is a bit questionable, but its what you have, so we'll trust those numbers.
Lap times:
A/Sedan is more of a race car, but they are really down on power and have some funky SCCA rules. IMSA Grand Sport is on some fairly hard tires, but you are faster than the latest Multimatic S550 there. It sounds like your car is closer to a TT3 car than anything else. The problem is that the NE Region of NASA has badly out of date lap records, but the 2:00 lap time seems a bit on the fast side - this is a fast benchmark for GRM's UTCC, held there annually. This time was set at the 2016 NASA National Championships, which were held there, and brought the fastest cars in the nation. Probably set on wider Hoosier A7s, and it would have had aero, so there isn't a great apples-to-apples comparison there.
Long story short - 2:16 isn't setting any NASA track records, but is faster than the latest GS race winner (2:16) or the fastest Mustang (2:18) there, so it isn't too shabby. Especially for 245s!
Clearly you can see how much smaller the Hankooks are. I got a smoking deal on them, knew they were on the small side, but how can you pass up a deal at $85/tire? Budget does matter when it comes to doing these events. I wouldn't be in a mustang if I was independently wealthy.
Fair point, and for HPDE, budget is always important. $85 R-compound tires are hard to ignore!
As I stated before, tire COMPOUND is more important than tire SIZE.
Well yes, I don't think anyone will argue with that. But you are comparing to one of the worst tire models on the 285, the Toyo R888R. The Toyo is so bad that in many classes that DO allow a 60TW or 100TW tire (GL Time Attack and GTA), most racers are still racing on "200TW" tires. The R888R Toyo is considerably slower than the RE-71R, Kumho ACR, or A052.
Now, the smaller DIAMETER tire offers two advantages over the larger diameter tire. Lower gearing and better braking. This was painfully evident as Porshes were killing me under braking.
Tire height is always part of the equation. As is total wheel/tire weight. Both of the wheels you are using are OEM style cast wheels, to heavy. But the 19" wheel and taller 285/35/19 tire are probably 5-8 pounds heavier than the 18" wheel and Hankook 245.
So you can see why I was dissapointed with the larger tire that I went slower on. The tire wear on the R888Rs is about 550 track miles in 3 HPDE days. (2 WGI, 1 Summit)
Again, not a surprise with as turrible as the Toyo R888R is.
I'm not adding camber to fit a 305 on the car, that's what the camber clan guys do. This is NOT a race car. It is a street car, that gets to see some track time.
Well the more tire width and grip you make, the more static camber you need to compensate for bushing deflection and added body roll. These two things go hand in hand. There is no one "magic camber setting" just like there is no one "magic tire pressure". But even with just a 245mm Hankook I suspect you'd see more even temp spread over the tread with -2.5 deg. Take some tire temps and see for yourself.
And to counter your point that this "is just a street car" you are running Hankook R-compound racer tires. With adjustable camber plates you could swap between street and track camber settings in "ones of minutes". Your shoulder wear didn't look awful but I suspect if you showed an in-corner picture of the outside front tire it would be at zero camber or worse.
This is a 2006 GT on 18x11" wheels and 315/30/18 tires. Even with -3.5 deg of static camber and MCS coilovers, loaded up in a corner on an autocross the outside front tire is "out of camber". And a radial tire likes a bit of negative camber when fully loaded, for optimum grip and wear. You don't need obscene amounts of camber to fit an 11" wide wheel, but the tires want more camber as they get wider and stickier...
I should PM someone here as to how Terry will chime in and tell me about all my mistakes.
Hehe, I do monitor this page so you don't have to PM anyone. Gotta counter the "tech" coming from a few HPDE champions that troll this place with bad advice.
Again, I've pointed out that the R888R is a bad tire many times (a 3rd tire street tire). Your data backs this up, getting punished by 3 seconds from a 245mm Hankook (which is a 2nd tier R compound) that is 30mm narrower. Guess what? A wider Hankoon Ventus would be faster still.
Funny story: we went to the UTCC event at Buttonwillow in 2008 with one of our first BMW E36 LS swapped cars. We ran a 275mm Hankook R-compounds on the 17x11" wheels we normally used, thinking that since Hankook sponsored the event we should run their tires. Wow, what a mistake! Our times were kind of sad (we started top 10, then began slipping) until we threw on two
old 305 Hoosiers we had in the truck. Just putting these worn out Hoosiers on the rear dropped our times 3 seconds over sticker Hankook R-compounds. Regret not bringing 4 fresh Hoosiers!
So of course compound matters. But... I would wager that a 315mm A7 would lop off a solid 8 seconds off the 245mm Hankook's time, possibly more. But A7 wear is much worse than Hankook, and the cost is a lot more than $85 per.
Once you taste the purple crack there's NO GOIN BACK!
For HPDE, keep doing what you're doing. Add a tick of camber (again, take some tire temps using a below surface pyrometer probe) and that data will likely back up the -2.5 deg recommendation. Once you can afford wider wheels and tires you WILL drop loads of time, that's just how this all works.
If you care about getting by on minimal budget more than lap times, then don't change anything, and ignore everything I post.
Cheers,
