Wideopen, I had the same results when I called "dealers" in 2012 when I found out GoodYear had put a number of tires on a "inactive" list, including all the tires used by JrFuel racers and most all other FED racers running injected alky. I called ALL the slick manufactures looking for a replacement for the GY 22.6 lb 31x12x15 D2585. I found the "dealers" were just looking at their catalog and really didn't have enough info on real apps, just sizes. I got much better info when I called the manufactures, case in point Hoosier told me their 31x12x15 weighted 33 lbs, and had a stiffer sidewall and would not grow much, their 32x12x15 slick had a softer compound made for door cars shifting multiple times, where I got the term "dead-hook, shift, dead-hook, shift" and the stiffer sidewalls has to do with the heavier door cars. The reason I focused on 12" tires is because rules for JrFuel and A/ND, B/ND slicks are limited to 12" . But during my search for choices of 12" tires I found out GoodYear would make another batch of D2585's IF I gave them a solid order of at least 150 tires. At the 2013 WinterNationals I gave them the order of 180 tires, mostly pre-sold, and we received them in Aug of 2013.
Bill, the 31x12x15, and 33x12x15 GoodYears are still on the "inactive" list but I have 170 of the 31's on a special order, due to be made this month, and hopefully shipped in May, so if you want some, call me and I'll put you on the list. BTW most are pre-sold, so let me know soon. I also have 150 D1288, 33x12x15 on another order, due to be made in May.
I agree with Bruce [ Dreracecar] most tire reps don't have much FED info. I talk to engineers, and production schedule guys.
Now to the question of what size tire should I run, well it does depend on HP, car weight , transmission , converter, rear gears, wheel rim width, and 1/8 or 1/4 mile tracks. Basic, the more HP and or the more car weight the bigger the slick, and maybe the wider the rim, of course depending on track conditions. For instance, Bill's FED runs 182 mph, which tells me he's making about 750 HP, and the D2585 on a 10" wide rim with a 4.30 or 4.56 rear gear, would be a good place to start, if his car, with driver weighs under 1500 lbs.
Our JrFuel, with the all iron 850 hp SBC runs the D2585 on 12" rims, at 5 3/4 to 6 1/4 lbs of tire pressure, launching off the trans-brake at 6400 RPM, with a 1.68 powerglide 1'st gear, and a 8500 stall 7" A-1 converter, and a 4.88 rear gear. Which is close to what the other Heritage JrFuelers run. Scott Parks with their new Hemi are running M&H 33x12x15 tires, but their car set-up is different with the motor location is 52" from the the rear axle, and converter flashing at around 9200, and launching around 9000, and shifting at 10,500, but then again the best Scott has run this year in his "JFB" car is 6.81. I also, just talked to a racer racing A/ND that ran some good numbers with 29x10.5x15 MT on 12" rim, on his 950 HP 14° SBC, with a 1.64 first gear, and I think a 4.56 rear gear. He went with the 29" tire I think, because he has a 12 bolt drop-out rear which has fewer choices of gears, and wanted to try higher RPM's. Of course these are higher performing FED's but i know many NE-1 cars running fixed Bracket 7.60 with the D2585's on 10" rims, and most in not all of the SWJFA racers running 7.80- 7.20's running the D2585 on 10", 11" or 12" rims. I have found going to a wider rim helps when we race tracks with not great traction.
As far as the weight of tires, the key is rotating weight, the lighter tires will "get-up-on-the tire" sooner, also one pound of rotating weight is = to 9-10 lbs of static weight. So if you go by the old idea of "take 100 pounds off your race car you'll pick-up a tenth", if you take 10 lbs of of any rotating weight, you will pick-up some ET. So Jake if you go from 33 lb to 22.6 lb tires it would be like taking 100 lbs off your racecar. And like Bill said you can run a bigger number rear gear if your tires grow, which will get you better 60' times, with-out over reving your motor.
And Yes, Bill running lower tire pressures will give you more tire speed, because the tire will concave a bit and run more on the edges of the slick. You can confirm that by checking tire temps with your infra-red temp gun right after a run, checking it across the width. I always check tire temps after a run to see if it's spinning the tire too much in the middle of the run.
I have not talked about the results I get from my RacePak computer, because I assume most racers on this site don't have a data computer, but I make decisions on tire pressure, launch RPM, and even converter stall by looking at the peak driveshaft speed right before the tire hook-up, which is mostly around 3 tenths into the run. I look for around 2200 rpm.
Now you all can try all kinds of combo's but I have in my over 50 years of dragster racing started out running what the fast guys have learned and are running, and when I was running as well as those guys started trying new stuff. As an example, when we were racing our dual engine BBC Top Gas dragster we wanted to be on of the the 1'st TG dragsters to go over 200 mph, we tried softer valve springs and went 204.
I hope this answers some questions, and I bet raises some more questions. On another post I will tell you the history of how the JrFuel slicks developed.
Feel free to call me 805-444-4489, Calif, Hayden Wheels.
