Author Topic: Rear Tire selection  (Read 39300 times)

Offline masracingtd1167

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Re: Rear Tire selection
« Reply #30 on: April 22, 2015, 02:02:00 PM »
Can't answer any of that but my 10.5 MT will spin with lower pressure and dead nut hook the slober out of your mouth at higher pressures  that is the exact opposite of what that tire has done on my past door cars FWIW .
The dragster is way different in lots of ways--it really digs crazy loose converter--my door cars did not
The math for lower weight on rotating parts will astound you at the performance diff it Should make--I am like you --doing this for fun so who cares but...real racers pee before a run and take the spare change out of their pockets
     Dave very interesting that your car spins more with less air pressure ! Could it be that with less air the center of the tire is not making as much contact with the track surface ? I pee before I run and I pee after I run ! I'm not sure if that makes me a real racer . I think it's just because i'm an old guy !!! Bill   

Offline dusterdave173

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Re: Rear Tire selection
« Reply #31 on: April 22, 2015, 05:25:35 PM »
I can't honestly say anything for sure--I have so few runs all on 4 different tracks so....The least run I made was at Rockingham--and the lowest tire pressure I have used so far and it hazed the tires off the line--really all could be in the tracks--early in year, test days , minimal prep--I need  a season before I start making many judgements at all  Fun as heck learning though!!
I have always had a fascination with fast cars at the expense of more normal character development

Offline masracingtd1167

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Re: Rear Tire selection
« Reply #32 on: April 23, 2015, 01:54:30 PM »
After talking to slick manufactures and some racers that pointed out all the 10.5 tires are designed for the 10.5 door car classes. So I think the biggest difference in those tires is a lot stiffer sidewalls to handle 3000+ lb door cars and softer compound to work with "dead-hook, shift, dead-hook, shift," etc.

I've never seen a 10.5 outlaw door car "dead hook"  From my observation it's a controlled spin for the duration of the run.

Do you care to expand on this?

I have a couple of questions, and I don't want to hi-jack the post, but here goes.

Disclaimer, I am known as an over thinker, and I don't want to be a smarty pants, but I am always curious.

There are a couple of JR. Fuel, Heritage, 4.99 minimum dial in racers on here, and there are also some bracket racers/nostalgia index racers that aren't concerned about the fastest ET, but more consistency and running the dial.

So here goes.  First, I see some opinions about "tire growth"  but why do you really want a tire to grow?  they way I see it, the more it grows, the less chance you have of having a flat contact patch?  Wouldn't centrifugal force push the center out?  Yes, I know NHRA top fuelers do this, but, they also have a huge wing. 

Second, I don't exactly understand the big deal about tire weight? I seen on Jegs the 10.5 mickeys were 33 lbs and the 32 12 hoosier's (D05) are 28lbs.  Yes, I know 5 pounds a tire is big when ET is in line, but if running an index or bracket, what does 5 pounds really matter?

Third, it seems that everyone wants their FED/Altered to "get up on the tire quick" and "wheel speed is king" Why wouldn't a stiff sidewall work here?

Just curious, not to be smart, all opinions welcome

Fire Away! 
          Jake I tend to over think things too but that's what racing is all about ! When a tire grows it is like having an extra gear for more trap speed . For most of us this helps us go quicker ! The heavier a tire is makes it harder to accelerate . Lighter is always faster and 5lbs can make a big difference . I have never tried a stiff sidewall tire like the 10.5 but I think you would have to change some things to make it work . The quicker you can make your tire go round the faster you will go . I run a soft sidewall tire and at the hit the tire will squat and hit the bar and after a couple turns come up on the tire . This has worked the best for me ! I hope this helps ! Bill     
« Last Edit: April 23, 2015, 01:58:12 PM by masracingtd1167 »

Offline wideopen231

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Re: Rear Tire selection
« Reply #33 on: April 25, 2015, 08:27:36 AM »
Another over thinker,normally gets me in trouble.
Stiff sidewall would seem to be able to go round  sooner.In fact I talked with 3 different MT reps and they all recommended the 3074S over the 3074. On post I started on tire size so as not to hijack this one.I had comment on 14" wide weight being more than 12".Yes it is but  not much,for some  reason in the MT lineup there is lot less differance than in GY. Nothing against GY I have ran them for decades. I just want to try the MT's because of tons of good comment ont them from bracket guys.

  I maybe over thinking it and come up bckwards will not be first time.Bad thing about thinking it thru you can make  good reason for things to work on both sides of the coin. Reason I say the non thinkers are blessed,  They don't come up with reason it will not work and just try it and eventually luck into something.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

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Re: Rear Tire selection
« Reply #34 on: April 25, 2015, 09:18:48 AM »
The problem with tire reps is that many are not familier with front engine dragsters and what their  needs are. Rear motor Comp & Super classes and door cars are what they see the most.

Offline masracingtd1167

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Re: Rear Tire selection
« Reply #35 on: April 25, 2015, 09:57:32 AM »
The problem with tire reps is that many are not familier with front engine dragsters and what their  needs are. Rear motor Comp & Super classes and door cars are what they see the most.
    And Goodyear stopped producing the 2 tire numbers that most of us use !

Offline wideopen231

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Re: Rear Tire selection
« Reply #36 on: April 25, 2015, 10:57:29 AM »
 Two dealers suggested stiff wall.Both said they had tried both on customers cars and they all liked it better.2 seperate calls,2 dealers half country apart. Either they got memo or had experiance with tire on FED's. Just saying.
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline JrFuel Hayden

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Re: Rear Tire selection
« Reply #37 on: April 26, 2015, 03:19:27 AM »
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.   
Jon C. Hansen

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Offline wideopen231

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Re: Rear Tire selection
« Reply #38 on: April 26, 2015, 08:26:44 AM »
Jon,

 As always very informative.

Would like your input on tire selection. Since combo little different than most and purpose bracket race consistency.

Car 225"
engine 50" out 526 Alum Hemi should do little over 1050 HP computer program calls for 1150 not to sure I buy that,no real world dyno YET.Normally pretty accurate given correct input.
rpm wise   power band should be 6000 to 8500
 1.68 with 6600 stall
4.11 at present changing gear is no big deal

 15x14 weld aluma star wheels,call them semi lite. Reason for 14 got them super  cheap.
 Hopefully car and my fata-- 1550 at very most,hey down 55# on driver. and not on race diet yet.
 goal is to run 1/8 mostly brackets and mid 4's if powers there it should not be issue. If I go too fast ,oh well. Not a hold you to thing just your input from your experiance . Computer fun what could happen but real world experiance normally wins out.
« Last Edit: April 26, 2015, 09:08:21 AM by wideopen231 »
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline JrFuel Hayden

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Re: Rear Tire selection
« Reply #39 on: April 26, 2015, 01:38:13 PM »
Mr Wideopen, yes you have a different combo, hard to find a race team to learn from with a different combo. So I just called a friend that races a alum 500" Brad Anderson type Hemi, on alky with a powerglide, but with 1.54 first gear, and 4.71 rear in 225" FED racing Heritage A/FD, BUT he runs a blower making about 1500-1600 HP. He is now running GoodYear 33x14.5x15 D2070, and his motor is out 46", at 1900 lb [ min weight for A/FD is 1875] running 6.40's in the 1/4.  OK not your combo, but I wanted a start point. The guy that bought his old car runs a 468" BBC [ motor out of a boat], with 4.11 and using GoodYear 31x14x15 D1984, but racing EZ 8.60 NE-2 class.
One thing I'm thinking is your 526 should make allot more torque than our JrFueler because of the engine size and of course longer stroke, longer strokes make more bottom end power/ torque, which I would think you might want the motor closer to the rear to get better traction with your 526. I would suggest you look at GoodYear 32x14x15 D1984., or 32x14.5x15 D1672, now both of these are on D-5 compound which is a hard compound, so it will help you keep the RPM up, and it's the the same compound we use. My A/FD guy has tried a couple of softer compound slicks and had traction problems, we think it might be the softer rubber would ball-up some and then spin.
One thing I wonder about is your 1.68 first gear, a 1.69 is a large carrier gear, where as the 1.68 is a smaller/ lighter carrier. Larger carrier is for the higher HP/ torque combo's, so you might want to check with your trans guy to make sure that is want you want for your 526. Over the winter we sent our trans to Rossiler to have checked-out and they said we needed to replace the 1.68 because it was showing some cracks. If it was me I would be thinking of stepping up the rear gear, since you will race 1/8 mile, like 4.71-4.88, just check for expected 1/8 RPM,  with your 4.11 I don't think you'll get to your 8500 range. Now if it turns out you keep breaking out of your bracket you can go back to the 4.11, but remember a bigger number gear is a HP/ torque multipiler, and help you until you get the rest of your combo figured out.
You engine location might help, since you should be able to have less weight on your nose. Have you weighted the car yet, our JF car with our all iron hemi weighs 1535, and with the SBC it's more like 1435, with drivers. BTW we run 4.40's in the 1/8 with our 4.88 gear in the SBC and 4.56 with the hemi.
How did you figure your expected HP ?
I hope this helps, let me know if you want to get either of the GoodYears, I can get you a discount., 805-444-4489
Jon
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Offline masracingtd1167

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Re: Rear Tire selection
« Reply #40 on: April 26, 2015, 01:46:40 PM »
Jon Thank's for the reply's ! Very interesting stuff !

Offline wideopen231

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Re: Rear Tire selection
« Reply #41 on: April 27, 2015, 09:54:10 AM »
Thanks Jon. My bad on the gear it is 1.69 not 1.68. Have not weighed car yet and hoping for less total weight than stated,never upsetr when they weigh less. Hoping for high 1400's,but with battery and cpl extra electronics trying to keep expectations realistic. Aluminum carrier ,aluminum pump in trans , minimze everything,plus drilling holes in holes to get air out should help.   Right now 4 gallon tank and battery on nose,215# driver hanging out back. Have fire bottle and NOS bottle(mostly topend and some midtrack) to mount that can be used for ballast also.

  The 50" out was changed during build after long talk with that Parks guy.The 4.11 is in because it was here. I have 4.30 and 4.56 I can get to try at any time. $.11 is leaving sme on table for 1/8 but not so much 1/4 mile.Not many 1/4 mile tracks we might run but a few and with bracket deal I need can do both combo.

On the expected HP number. Don't laugh to hard. I used desktop dyno program. Was skeptical at first. After running number real worl combos thru it and getting aroun 1 to 3% differance in real dyno number I have come to respect it more.  If you give it real numbers for headf flow,induction system,real compression and accurate cam specs it will impress you with its accuracy. I am amzed anyone can write a program that can run as many compariosns and get in ball park much less as close as it does.Main thing I have found is cam and HEAD FLOWS,imagine that.

If interested and have real dyno and numbers needed I can run them thru program and see how close it comes.Kind of hobby checking and working with it while wife watchs tv at night. Alann Starr once told me "If you go a day w/o learning something new you wasted a day of you life." Pretty sure learning anything on engine would qualify with the old man.

  Sorry but glad to see Im not only finding it hard to find info on simular setup. Heck if it was easy it would bore the heck out of me. Done a lot and not much of has been picked because it was easy.

  Thanks for input and info you found out from contacts.

To Op sorry not trying to highjack thread,figure info in public room better than PMs where only one learns.
                                                                                                  Chris McBride
« Last Edit: April 27, 2015, 10:12:59 AM by wideopen231 »
Relecting obama is like shooting right foot because it did not hurt enough when you shot left foot

Offline JakeB23

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Re: Rear Tire selection
« Reply #42 on: May 01, 2015, 09:30:17 PM »
This is good information.

What about air pressure? What is everyone running for air pressure?

Offline JrFuel Hayden

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Re: Rear Tire selection
« Reply #43 on: May 02, 2015, 12:03:37 AM »
Jake, good question. well lets see "what is everyone running for tire pressure" ;
Scott Parks ran 4 1/2 lb in his 33x12x15 on 12" bead lock wheels  in their NHRA record [ 6.76, 197 mph] holding A/ND with their 385 ci SBC with monster flowing heads. Scott and Frank's car has the motor out 52" to help keep the tire speed up since the big head motor makes less torque than any other A/ND racing. Again less tire pressure gives you more tire speed.
i just talked to a racer just having fun in his low budget FED running in the 8's using 10.5 slicks running 7 1/2 lbs of pressure.
A friend racing Heritage A/FD with a blown alky late hemi runs 32x14.5x15 GY runs 6 1/2 lbs and 6.40's
We run 5 3/4 to 6 1/4 lb depending on track conditions on 12" rims with D2585 GY 31x12x15 running 7.0's @ 188 mph.

So what is everyone running ? If you are asking about what you should run, as you can see, it depends on your combo, clearly if you are running a 355 ci SBC or a 526 ci blown alky BBC you will need different slicks, rim width, pressures, launch rpm, weight of car with driver, weight on the nose, height of wheelie bar, trans gear, rear gear, and converter.
 I'm sure you have heard this before "it's the whole car combination". 
Our driver, when he was racing his own JrFuel "A" car picked up almost 2 tenths by changing converters, nothing else. Kinda like the last piece of the puzzle, it let the motor run in the RPM range it wanted.

Jon Hansen, Hayden Wheels
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Offline JakeB23

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Re: Rear Tire selection
« Reply #44 on: May 10, 2015, 06:14:52 PM »
Ok, I wanted to update this post since I had some questions, and now I have some results.

I have a 225" FED that runs 5.40's in the 1/8th and 8.70's in the 1/4, (well, did atleast)

I started with 33 x 12 MH slicks, tried 7-9 psi, settled on 8, and car went 1.22 60's

I borrowed a set of 32 x 14 Hoosier's, tried 6-9 psi, settled on 7, car also went 1.22 (fastest)

I bought a set of 3069W 33 x 10.5 MT slicks. I thought the $269 a tire was reasonable, and at the time Hoosier 33 x 12's were 3 weeks out, and 33 x 12 GY's were a month out.  I'm Impatient, and I wanted to stay with a 33" tire.  Also I had used to run 28 x 10.5's MT (M5) compound on a 6.80's bracket car that didn't hardly need a burnout to hook, so I wanted to try them for my FED.

I tried 6-10 Psi and settled on 7.  Car went a 1.18 60'    Fastest 60' I've ever had, now I did have to slow down the shift this weekend to run an index, but I CAN'T WAIT to unleash this thing and see what it will run now!

Disclaimer. I don't know how old the MH or Hoosier's were, but there were both at least 3 years old.  The Hoosier's I ran on a 15" rim, so there was definitely added weight for that wheel/tire combo.

Either way, I wanted to let everyone know my results as this is what helps people learn.