Originally Posted by
JDNSW
That is "a" chassis number. Whether it is yours or not will depend on the history of the vehicle - which you probably don't know.
The definitive chassis number will have been stamped on the chassis. Australian assembled ones will have the number on the LH rear back spring hanger, facing out. UK assembled ones should have it on the top of the RH chassis rail, near the front - usually in the engine bay I believe. Vehicles assembled elsewhere - who knows! The stamped number is likely to be invisible due to rust, mulktiple coats of paint, or all of the above. And it is possible the relevant part of the chassis has been replaced.
The standard tyres for your Series 1 are 6.00x16. 6.50x16 was the optional larger size. 7.00x16 was often fitted, especially in later years, but was never even an option for it. You are likely to find it a bit overgeared with 7.50 or even 7.00 - plus the speedo will be out, and if it has the original wheels (231601), these are five inches wide, too small really for 7.50. The trouble is that 7.50 is the easiest to find today!
The 107/109 came with 7.00 tyres as standard.