[TheReferee]

Alec is not quite right in his statement. the actual wording of the rule is,
The Rule covering this situation is 3.7 :-

3.7 ‘Commercially Available’ - Where the term commercially available appears in BRCA documentation in regard to racing equipment allowed in 1/10th Off-Road Sanctioned events, it is defined as any item or items being accessible for purchase by anyone and therefore must be or have been available in UK retail outlets in reasonable volume at any one time.
New versions of tyres/compounds or tyres that have not been produced within an acceptable time, as deemed by Section officials, that are therefore not easily available to all competitors may be disallowed.

in the case of two row studs they comply with the first part in that they were available and so could be used, however the second part of the rule acknowledges that the pool of tyres has dwindled to such an extent that they are no longer available to all and therefor are classed as no longer available.

there is no set time on when we would apply this rule for example if Schumacher was to stop producing stagger ribs today, it is likely they would remain in good numbers in shops and in racers pit boxes for a couple of years, if losi stopped making there stud tyre today then it is highly likely that there would be none in the shops and not many racers would have them, therefore they would quite quickly made illegal.