runflat with non Runflat

Gary, I know your stance about mixing runflat and conventional tires but I just talked to my local BMW dealer and he said there is no issues with mixing the 2 tires as long as they are on different axles. This lead me to ponder what we have been doing for years with conventional tires. When one pair wore out we replaced them with what were available at the time. many times we mixed hard compound tires with soft ones on different axles. This is no different than using a runflat and a conventional.

I have searched and searched and have found nothing except for opinions on this everywhere. Do you know of any published study findings about this topic?

Whoever you spoke with at your local dealer is misinformed on this matter. Check with BMW of North America (or Germany if that is where you are from) directly if you would like BMWs actual stance on the matter. Tires have come a long way over the years, as have vehicles...do not mix.

The tire industry trade organization, the Rubber Manufacturers Assn. issued a service bulletin in 2010 (ref: TISB Volume 47, Number 1) that specifically recommends against mixing conventional and runflat tires, except in an emergency situation on a limited, temporary basis. There are many threads in other forums with reports of guys mixing in axle pairs and experiencing major handling issues. E90 cars are the most common BMW model to use run flats, so I would suggest a Google search with "E90 mixing run flats" if you're searching for those threads.

Here is a more generic article about mixing in general : http://www.tirerack.com/tires/tirete...jsp?techid=136

That being said, the Tire Police won't come and arrest you if you mix them anyway...