Hello and welcome Sam.

Yours is an independent and these were designed for the larger tyres, consider that all steering and most of the braking is done at the front wheels and it would be sheer folly to put smaller tyres on the front as they have much less contact area, or in simple terms, less rubber in contact with the road.

Your clonking noise could be one of a number of things:

Propellor shaft universal joints are prone on these vehicles, basically they are designed to wear or snap as they are the cheapest component and the easiest to replace, so check all these and ensure they are fully greased, and grease them regularly.

Freewheeling hubs are prone, often its a lack of maintenance which allows them to fill with dirt or water, the dirt compacts and hinders their operation, and water obviously corrodes them internally, so check these and if necessary strip them and clean them, then fill them full of grease.

Independents have front driveshafts instead of a full axle, each driveshaft has two CV (constant velocity) joints, check these for wear and the rubber gaitors which cover them for tears or splits as this will allow mud and wet into them and destroy them in a short time.