Tyres Ford Bantam 1600i
The Tyre sizes are 165/80 x 13
Are you are talking about the type of tyres on your Ford Bantam or on the ones on your box trailer? However, we are a European tyre buying guide, and since the Ford you mentioned wasn't produced for the European market, we don't have the info on your vehicule in our database.
In general, you don't need to change your car tyres when towing. If you want to make sure the tyres of your box trailer will be sufficient, you need to check the load index, to make sure they will support the weight of your load. More info on the load index:https://tyres.rezulteo.co.uk/tyre-advice/i-need-new-tyres/how-to-read-tyre-markings/read-understand-tyre-markings
Hope this helps.