The ECTA rule book for 2007 indicates that OEM motorcycle tires are OK up to 125mph at Maxton. This year there is an update to the wheel size specs that says that 15inch in the minimum. I suspect there would be an exception for stuff like pocket bikes, scooters etc., but that is just my very unofficial opinion. The rule book lists Scott Guthrie as the contact for 'Correspondence related to motorcycle rules . .' It lists an email address of ecta-mc-committee@yahoo.com. Mr Guthrie is a regular on this board so he might see this thread and respond directly right here. When you send an email to any official at ECTA it is suggested that you include words in the subject line like “ECTA” or “Maxton” — so your mail does not get tossed with the junk mail. They are apparently getting hammered with SPAM.
BTW There should not be any problem timing your bike at those low speeds. In addition to the electronic clocks the tower also has a calendar.