Author Topic: Tubeless tyres/tires  (Read 6868 times)

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Offline whipster

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Tubeless tyres/tires
« on: April 07, 2004, 12:26:00 AM »
I am updating a Lakes Modified [DLRA calls it a Speedster!!] that ran at Lake Gairdner a couple of years back and note the rear steel belted radial tyres are fitted with inner tubes.
 
 The previous owner fitted them in line with the rule "Tubes are required, except for racing tires expressly designed for use without tubes".
 
 I contacted Dunlop for advice if their modern radial tyres are compatible with inner tubes and if so fitted would the HR/VR/ZR speed rating still apply. The answer was NO!
 
 It would seem logical that if a HR/VR/ZR tubeless car tyre was fitted to an approved modern car JJ type rim, and the vehicle weight was within the rated tyre load capacity, it should be acceptable up to its manufacturer rated speed.
 
 I searched the archives but didn't find this subject mentioned before so it maybe that the rule book has been misread.
 
 Can anyone confirm that the SCTA rule book actually means that an inner tube MUST be fitted inside a modern steel belted 'tubeless' radial tire?
 
 Regards Ted Robinette  http://clubs.hemmings.com/clubsites/wocv/willywilly/willyrac_18.htm
 
  <small>[ April 08, 2004, 09:22 PM: Message edited by: Ted ]</small>

Offline Rick Byrnes

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Re: Tubeless tyres/tires
« Reply #1 on: April 13, 2004, 09:57:00 PM »
Ted
 On and off I used BFG R1 tires, Front runners, and even Winston Cup Talladaga tires (didn't work for me.)
 Back then Michelin/BFG was a sponsor and I posed the same questionto the engineering staff. Answer: NO TUBES! end of discussion.  They further qualified that the friction between tube and tire will generate excessive heat.  Now, I feel they were being very conservative, but then they have a right to.  I ran no tubes, and had no issues with technical people.  For a number of years my speeds were just around 200 +- 3 MPH with both R1 and LSR tires.   I think in an under 200 mph car as long as they meet the speed rule they will be just fine.  Remember they were designed to run with no tubes (at the speeds certified).  Do keep in mind the better effect of the skinny LSR tires.  I had better consistancy with them.  Depending on lots of variables, wider is not better.  
 By the way, your roadster looks neat!
 
 Rick Byrnes
Rick

Offline whipster

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Re: Tubeless tyres/tires
« Reply #2 on: April 14, 2004, 02:31:00 AM »
Rick
 Thanks for the Michelin/BFG feedback re not using tubes. I have a few trips to BNI and El Mirage under my belt and have preached the skinny tyre benefits here. Unfortunately not all racers in Australia have such first hand experience and instead rely literally on what they read in the rule book which states that "Tubes are required, except for racing tires expressly designed for use without tubes".
 
 This is in the SCTA rule book, as well as copied into the DLRA version, and perhaps taken out of context but has lead to passenger car tubeless tyres being fitted with inner tubes contary to the tyre manufacturers advice.
 
 I teach auto and the only technical reference I could find, re fitting an inner tube, was as a temporary 'get you home at reduced speed' fix. Occassionally we get a tubed wheel/tyre in class for punture repair and often it had failed because the tube had rubbed through against the ribbed inner casing of the radial tubeless tyre leaving little balls of rubber inside the tyre, and a hole in the tube.
 
 Thanks also for the kind words re the roadster. The www pix are of it as built and raced previously by Rod Mappin. I am in the process of purging it of the Ford front axle   ;)  and installing a 1939 Willys beam axle with parallel springs. Being based on a narrowed and shortened 1928 Whippet tourer body and chassis with Willys flathead 4 engine it is now called the 'Whipster'.  
 
 Sure would like to see enough of these traditional style 'Lakes Modifieds' turn up at the lakes to form a new 'LM' class.
 
 Ted Robinette