tires

[ronnieroadster]

 Our experiance on the D/BSTR roadster at Maxton by viewing photos and video taken crossing the finish line show the M/T drag radials growing a lot in diameter at 200 to 206 MPH. The tires do not display the C shape like the top fuel boys experiance they are still very round just a lot taller. The increased diameter adds to the overall final gear ratio which of course adds a bit more MPH.
   On my Lakester the photos and video taken at the finish line at Maxton show the M/T drag radials I run have grown in diameter even at the lower speeds I have run which to date is just under 175 MPH. The added diameter change has helped me gain a bit more MPH over what the Mark Williams wonder wheel figures say I should get with the RPM, gear ratio and tire diameter I run. So far Im very happy with the results using the drag radials.
 Ronnieroadster

[greenjunk]

I guess my question is how can you tell the grow. To say they grew an inch or two from a picture taken from 100ft away is not really proof.  Do you have a gauge to measure?  Based on my pictures I haven't seen the growth. Rumors of the tire separation problems were caused from too little pressure. Not from the speed itself. Host went faster then anyone with mickeys and had no problems. How do cars 20 mph slower have issues. I didn't know race tires had a warranty....  I didn't know race anything had a warranty an. Guess I wouldn't expect it. I have blistered. Bran new mckey t on the dyno tho

[Fheckro]

Hmmm. Interesting thread.
 I am new to land speed racing but I have been a Michelin research engineer for 5 years now.
 I understand the need for traction but why drag radials? I know Michelin (as well as other manufacturers) makes several sports car tires with very soft compounds that are intended for speeds in excess of 200mph. They are the “(Z)” rated tires (not to be confused with “Z” ).  I know drag radials (or any drag tire) will beat these tires off the line but the (Z) should run circles around drag tires at speed. They are designed for extended high speed driving applications on “super cars” and they are sticky. They won’t grow like drag tires so why wouldn’t they make a good LSR tire? Just curious.

Fred

[redcatch]

If you are doing 170 to 190 My guess is that a pass takes 20 seconds or so. Even at 201 to 206 around 20 or so seconds. Not very long and the tires won't be in that range until the very end. I would guess tire separation could be caused from bruising . If you tow in the trailer with your race tires there is one spot that will be abused the entire time. I have also had a 12 ply tire that was brand new come apart . I had hit a chuck hole at speed on the way to Bonneville. Not unlike what we did all the time at Maxton. Thats why its important to run your tires all the time. A bruise will start a seperation that will lead to total loss of the tire. Keep looking at them. I also can not verify that drag radials grow. As a rule, the tires we run are too narrow to balloon. My program gives me a speed for RPM. It is always high. I either have drive line slipage or tires are slipping. Twice I have flashed the traps at a RPM that I was sure would produce a 200 MPH hat ,only to find out that is was not that fast. So were they getting smaller. I think not.

As a side note I have run almost the same tires above 165 for 118 miles .

They got greasy at the finish but were still okay.

[redcatch]

My two cents on "Z" rated tires.  They Will do okay. All the road racing rubber I have run over the years required heat to work. They also are designed to turn. That should require very different side walls. Also every "Z" rated tire I ever ran I had shaved down to 3/32 before they worked. I do believe the rolling resistance is higher. As simple as it sounds on the LSR stuff "for me" it has boiled down to how easily does it roll. How much traction does it give me in third. Most of the cars are running 700 HP and up. Those that are hitting 200 I would guess are 800 . That will produce slippage at speeds. I don't much care if the car pushes or is tight.  We have alot of caster and a little toe in. As a rule high speed cars that turn, run toe out as it causes the car to turn in faster. There are a jillion suspension twicks that cars that turn use. Cars that go straight have the ability to go straight and continue going straight. I for one am looking for every little thing I can find. I would have Ceramic Bearings on the front end and in the rear if I could afford them. After I win the lottery maybe. But in my mind "small as it is" I want a tire front and back designed to go straight. I only need to turn at the turn off.

[Fheckro]

that should read (Y) speed rating which are marked "Z" but are different. sorry for any confusion

[manifest]

I can't imagine that a radial (M/T, MH, Hoosier, GY, BFG, etc.) would beginning to fail in just one mile.  The radial drag cars are doing burnouts then lauching and having sub 1.20sec. 60fts. with them and the life of the tire is only the sidewall lasting.  As for the Y/ Z rated tire I have only ever seen ones made for production style wheel, i.e. 17" and bigger and most do not have much hieght.  BUt is may be something to look into.  Right now i am still leaning towards the 28" GY radial for our Datsun.

Zach

[jl222]

Our experiance on the D/BSTR roadster at Maxton by viewing photos and video taken crossing the finish line show the M/T drag radials growing a lot in diameter at 200 to 206 MPH. The tires do not display the C shape like the top fuel boys experiance they are still very round just a lot taller. The increased diameter adds to the overall final gear ratio which of course adds a bit more MPH.
   On my Lakester the photos and video taken at the finish line at Maxton show the M/T drag radials I run have grown in diameter even at the lower speeds I have run which to date is just under 175 MPH. The added diameter change has helped me gain a bit more MPH over what the Mark Williams wonder wheel figures say I should get with the RPM, gear ratio and tire diameter I run. So far Im very happy with the results using the drag radials.
 Ronnieroadster

  Thats how we found out our tires were growing, when the 5 mile exit speed was higher than the rpms that were turned and what the computer and dream wheel said they ought to be. Rpms were about 300 less, adding 11/2'' tire growth to tire diameter  made the time slip and rpm to come out right for our 275 mph time slip.

                 JL222

         

               

[ronnieroadster]

Greenjumk
 Your asking for a measurement? Dude the tires grow at speed THE PHOTOS at the mile PROVE THAT bottom line if you use them make sure you have addtional clearance in the fender area so you do not rub them causing a failure at speed. The drag radial tires are awesome one less detail to think about for a LSR vehicle.
 Ronnieroadster

[greenjunk]

I've used them for years with no clearance problem. I just don't see how you can tell from the picture that the tires grow. From my calculations I'm not seeing any diameter change at 200 and I run a narrow wheel and a wide tire providing even more opportuniy for growth.  That's why I asked whether you had a way of measuring or if it was your best estimation based on what it looked like

[ronnieroadster]

Hi David
  The added clearance to the ground on my Lakester under speed is at least an addtional 1 to 1-1/2 inches under the rear of the belly. IM very concerend with keeping the car as low as possible {who isn't}the move to Ohio will allow me to lower the car since we no longer should have any concern with rocks and any rough surface to tow the car on. After viewing the 8x10 action pictures of my car carefully I have determined I can go a bit lower with the suspension in the rear to compensate for some of the height gained at the finish line. Not sure if one inch lower is possible but IM sure going to try and lower it that much and see if can even get her out of the shop and onto the trailer.
 The tire growth on the roadster was great enough to cause the tires to rub on the fenders a bit of tire smoke was visable on the top end the tire growth was definitely greater on the roadster at a much higher speed.
  Ron

[greenjunk]

Got it. That makes more sense. I'm probably not seeing the tire growth because I'm getting 250 of downforce at 200 plus I have an extra 175lb of balast I'm thinking that's keeping the tire looking more "normal". You don't get the priveledge of downforce in a tanker

[Kix]

We use the drag radials at Maxton.. and have not had a problem even though we weigh over 4,000lbs and are running close to 200mph.  I am convinced they do grow, based on our RPM/Speed calcs, but would be interested to see how much the growth difference is at varying tire pressures for the same speed.  Let's put my GoPro on the tanker and see what they do up close!  I would do it on my truck.. but we are about out of tire room already and we would have to provide light in the wheelwell......

Kix

[Cajun Kid]

OK,, seems like maybe I should buy the M/T ET Drag Radials,,, 235/60/15 (26 X 9.50 X 15)

The M/T's on the Vicky are 27.1 tall and 10.5 wide,,, they are to wide and to tall,,,

My experiance with the M/T's (on my 1933 Vicky sedan)has been much better for launch up to 1/2 mile,, but seemed greasy at the finish..
(it was a brisk cross wind that day,, and I may not had enough air in them,, only 26psi)

I will order the M/T's for the Studebaker,,, any starting air pressure suggestions ??

Charles

[ronnieroadster]

Hi Kix
 Great idea about the Go-Pro it remined me I did use the Go-Pro on one of my last runs pointed rearward I wanted to see the chute deploy. Looking at the video again it looks like to me using my old eyes I can see some increase in tire height.  The video would have been better with no cloud cover and not running over the patch to view the tire better but its interesting anyway I think.
  The car was moving around a bit a combination of needing a little more suspension work and a driver{thats me} who's not so nervous kind of like driving a go cart on steroids.
   Ron

http://www.youtube.com/watch?v=yTd5W1psJa8&feature=related