It may be possible to fit a tyre with a bigger aspect ratio to give a taller sidewall, but we would not advise increasing this by more than five - so if your current tyres are a 40 profile we would not recommend anything more than 45. You may also find that switching from runflats to conventional tyres will improve the ride quality, as runflats have stiffer sidewalls to give them strength but this can result in a harsh ride.