Right ok couple of things- The wheel issue is probably the centre bore. If the alloys are off an MX5, Suzuki or some other makes the centre bore is too small (you need 56.1mm the old mx5 is about 54mm) Alloys are hub centric- you need to get them machined out to fit the hubs or machined oversize to fit a reducing spigot ring. If the centre bore is correct check that the offset is not to much and the inner rim is not rubbing on suspension components. The tyre size you need is 195/50/r15. Your car does not have the same rolling radius as the MB6/MC2 (that is a downsize on them but not yours) likewise some of the MA models. Use the stock size on the sticker in your drivers door shut, put it into a calculator online and use the related sizes it recommends. Tyre size is the final gearing for your car deviating more than a couple of percent can really duck up all kinds of things from the speedo to fuel economy, torque etc. If you feel the need to go wider on 15's it is possible but 195 is a good compromise between grip and efficiency.