I'm going to replace my run flats one axle at a time with conventional tyres. I need a space saver spare - what size wheel and tyre do I need to use on my car with sizes of Front 225/35 19, Rear 255/30 19?

Space saver spare is restricted speed and only a limp to a garage job and as your car is rear wheel drive it wont matter as long as it meets the spec in your hand book. My fat X5 I carry a couple of cans of tyre goo and a small compressor (BMW actually do the same as a kit) Mine cost about a 1/3rd of their price.

I have some tyre goo, but a tyre place told me today that once you use it the tyre is unrepairable. Looking on a US Youtube video, a guy suggests a compressor and a repair kit. Not sure what the repair kit contains, not a lot I guess at $7.99.

First I have owned this X5 for 10+ years and in that time suffered 1 puncture and that was a slow puncture, so my experience is that a puncture with modern tyres is fairly rare. I went to the tyre shop and the fitter said "sorry mate we can't repair it as it is close to the edge" as my car has the complication of being 4x4 and a staggered wheel set up plus having suffered the consequence of mismatched tyres on my previous X5 what to do? Do I buy 1  tyre (tyre fitter happy to sell 1) or 2 either choice may give rolling radius issues and cause transmission damage? Do I buy 4, that would please the fitter. Or do I put the goo in and inflate the tyre which I am told is scrap anyway. Yep I put the goo in and it covered another 5k before I had to change all 4 due to wear. I think the biggest danger to tyres is side wall damage from damn potholes (current favorite hobby horse) we have section of road locally which is like a plowed field, it has cost a neighbour 3 tyres and no compensation as the holes are marked!! You just can't see them when it has rained and they look like a puddle?

I have seen the plug repair kits but have never tried them so can't comment, but I do know the goo worked for me that was about 6 years ago now. I do tow a horse trailer and go mildly off road so my tyres do get proper use and this is the second set since the "puncture"

I guess we all read as much as we can to gain information and then make our decision that is all we can do

Dave