The K1 and K2 were originally specified with a 625-16 crossply tyre, with is no longer available. 600-16 is an available size alternative, and well served with performance tyres. If a radial is required, then a 600R16 or 185R16 could be fitted.
The K models were Allard's more road-orientated sportscars, compared to the J models anyway. Unusual looks, and chassis and suspension design that was both ancient and innovative at the same time, the K1 and K2 drove well and had good V8 power, either from Ford's engines in the UK, or progressively bigger and scarier US types. Essentially, the idea that spawned the Cobra, Interceptor and so-on. The K3 was completely restyled to look modern and be more luxurious. BUt the US target market wanted its K sportscars much more raw, so it failed, despite its powerful hemi engine in that market.