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The spare included in my 73 S is a Dunlop SP57 tube tire...I eventually want to display that tire as my spare on the original Fuch 6X15 and am curious what it is about the tire construction that required the use of a tube, i.e. would it not properly seal if I did not use a tube? Thanks!
They came with tubes, but I converted mine to tubeless by changing the valve. You can go either way.
Surely the SP57 is a Tubeless Tyre as it is radial construction with Rayon belting.
They may have been supplied with tubes when new as some 911 Rims don't have the safety beads t hold a 'soft' tubeless tyre to the rim.
If you look inside a modern radial you find very rough surfaces which are incompatible with tubes and cause chafing of the surfaces and overheating.
Tube tyres used to have very smooth surfaces and were 'powdered' with French Chalk to minimise friction.
I've always had a dilemma about running modern radial tyres on an old deep 6 Fuchs rim. Run without inner tube and worry about the lack of a safety bead, or with inner tube and worry about the incompatibility described. Which is less risky? And does the view change between road and track?Quote:
Originally Posted by chris_seven
We have been running (on the street and track) early 6s...and late "flat" 6s tubeless since 73.
BTW, the safety beads are not related to tubeless tires. They were developed for a early version of run flat...long before tubeless tires were available.
Even today, there are wheels that don't have safety beads.
The main difference on the early 6 is the stem hole. The stem hole should be modified for tubeless snap in stems. The late "flat" 6 doesn't need the mod.
However, there are tires that are tube type that won't hold air when run tubeless...
H
I believe that Porsche started to use this feature on steel rims in 1968 and alloy rims in 1972.
Goodrich launched the first Tubeless tyre in 1947 and they were in very common use by the mid-50's.
I thought wheels with 'safety beads' were introduced in the US from around 1950.
The first Run Flats were introduced in about 1967.
Having had tyres come off rims on rally cars I always worry about the lack of this bead on early wheels with 'sticky' tyres.