[CMOTD]

There are much better tyres available than stock manufacturers' ones but compatibility is a huge issue so there is no one make fits all solution unless you are prepared to replace wheels and axles as well.

The default compromise is urethane tyres which are available from a number of cottage industry sources. They don't give quite as good a grip as Slot.It or NSR but are usually way better than stock ones and are available to fit the vast majority of manufacturers' rims. 

You may need to hunt around a bit but check out WaspSlot's range for starters. Ortmanns are also very good although currently unavailable due to the UK supplier's flood problems. There are many others but they are often located abroad and Paul Gage is probably the best known. Make sure that your club allows urethanes though, some are unnecessarily prejudiced against them.