I have the original Michelins on my 4.6 at the moment as, it has only covered 14k, so have not had the chance to look at changing. But my dad is running the toyos on his 4.6 and from time to time we would swap X's and I cant feel any difference in the tyres? The toyos seem like a good option, they are also a bit cheaper.

Just becuase the treadwear rating is higher doesn't equate in any way w/"better". Maybe better for you cause they last longer, but not better grip and feel etc. The Diamaris is a summer sport tire designed for max grip, even breakaway and good ride etc, not neccessarily longest life, just not a priority. With that said, I rarely go with OEM cause in most cases there are better choices, but the Diamaris is an exception as it is a very very good tire by any standards. If you don't need the maximim grip perhaps the Latitude by Michelin is a good compromise, 420 treadwear (twice that of the Diamaris) rating and all season etc. Just don't expect the same super high grip in the dry. Just my 2 cents.

If the Traction and temperature ratings are the same, and the treadwear is higher, then doesn't that equate to a better tire??

Sorry, not that simple, otherwise the latitude would be better than the Diamaris so why offer both from the same company, especially in the same price range. That traction rating is relative, very broad range can be a A. Using the example above, every all season tire is a compromise. The Diamaris is less so due to it's summer only rating, and I would assume that it's a better dry grip, turn in, handling etc tire. To what degree is up for debate. But it is aimed for the performance SUV market for max performnance. The latitude is compromised by it's all season performance (rubber must remain softer at low temps, must be able to handle at least light snow, has to do well in rain, max grip is down on the list. Trust me through, we never come close to a tires potential on the street. Ask anyone who has participated in a track day. What these tires do for untimate grip is amazing. The higher treadwear tire may be the right choice for most folks. Again, just my opinion.

WE are way off topic here, but appreciated non the less, however copmaring a all season is not the same. the proxies is a high performance tire like the diamar, and still has a higer tread wear, that is quite different then comparing to the latitude.
but in any case I jsut wanted to know if anyone had any comments on the tire difference if they used it or something else equivelent.

I believe the Toyo is an all season tire as well...same compromises being made. Regardless they all work fine on an X5 though some have reported excessive noise w/the Toyo's as they wear.

He never stated the Diamaris were bad. He was asking whether there were better options than the OEM tires.

What he indeed stated, was the fact that OEM tires are usually not as good as they could be. Which, in his own special case, could be very true.

We all know that the engineers go a great deal to test tires for these cars, but the choice is not only based on performance alone, but also on economics. Tire manufacturers work in conjunction with the car manufacturer to produce a tire for that specific vehicle. These tires, for the most part, are a great compromise, because they have to suit all types of buyers (in contrast to an owner who is looking for a tire that would suit his/her specific needs). The original tire manufacturers sell these tires to the car manufacturer for a hefty discount (pretty much at cost). Later, the tire manufacturer makes up its investment on people like you, who believe the OEM tire is the best way to go.

This fact, doesn't mean that other tire manufacturers cannot produce as good or better tire than the original one.

I have 3 M cars and none of them use the OEM tires. For my driving style and needs, the Michelin Pilot Sports 2 are a better tire than the ones that originally came with the cars. Which doesn't necessarily mean the "BMW engineers were wrong".