Your tyre’s can last up to 5 years or more, If looked after. Exceeding 7 years is the time you need to replace them. They should never be used after this time. If you was to use tyres after 7 years you are putting yourself and others in danger, it is also illegal.
The only way your car and caravan connect to the road is through the tyres you have on your car and caravan. If you look after them you will have less chance of a accident and needing to change them before your 7 years.
Carrying a spare wheel, a compact spare or a tyre sealant kit is a good idea incase it's needed.
Always check your tyres that they are suitable for use when towing.
There is Run-Flat car tyres but its not something I would advise as in some conditions they arn't suitable for towing a caravan.
You will need to ensure caravan wheel nuts are checked and tightened to the correct torque but don't forget that over tightening nuts can be just as bad as having them too loose.
Brakes are really important and can cause terrible accidents if not maintained by rightly trained mechanics. It's important for you to check on your brake mechanism and cables to ensure they are in working correctly. If you have any worries, you can have them checked by Stewart Morleys Caravan Storage.