A US gallon of gas weighs in at 6.3#/gal.
Adding another 65# to 70# over the rear wheel could have some bad mojo on the handling of the M3W.
In 19" tires, I highly doubt you'll get anywhere near that type of speed rating. If you swapped out to 18" front, you may be able to get tires rated that high. The rear tire may also be problem as that size tire is usually not used on cars that could get anywhere near that speed, so tire manufacturers won't spend the money making a tire that no one can use.
I do wish you lots of luck. I also agree with the full on roll cage as a protector, just in case.
I could see you going to TX where they run that speed thing on the closed freeway of something like that. You'll need a very long run at this.
Here's a VERY simple speed, rpm, tire, ratio calculator.
Enter in the 6000 rpm, 25" tire dia, 160 mph and it tells me that I need a 2.79 final drive ratio. That probably isn't too far off actually.
CLICK HERE FOR THE CALCULATOR 
