SVA / IVA
Is SVA/IVA required or not? According to VOSA if the car is already registered then it is not eligible for IVA (although there is now a voluntary IVA). If it is a new build then you can apply for IVA.

Full details of the IVA requirements are in the VOSA manual and you can access a copy (valid Oct 2016) via this link: IVA Manual for passenger vehicles

This is a large PDF file so may took a few moments to open.

Wheels & Tyres
This is a link I use frequently for checking the different tyres and wheel sizes that will suit my vehicles. Means I don't always have to replace like for like (some tyres can be rather expensive) but instead can change tyre configuration and maybe find something which can be same or better quality/performace but cheaper.

http://www.rimsntires.com/specs.jsp