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Bonneville Salt Flats.
Played around out there early in the summer. The salt was still on the wet side with thin pockets of standing water.

140 mph indicated, so about 135 with little sweat. I lifted. She had more to go. X5 had a Conforti Shark Injector tune with 7k redline and some intake and exhaust mods.

In all honesty, I was at the salt flats doing an efficiency test in which I made an 8 mile oval with cones. I was clearing the mid 30's under controlled conditions. This was just a trial run. I'm working on an aerodynamic under-tray with a modified rear diffuser. The air does tumble around under the car at speeds. If it can be stream-lined to reduce any high pressure areas it would be more efficient and reduce lift and drag. Anyways, long story short, I decided to get one good high speed run in.

For fun, here's a clip from my open AA headers before the rest of the exhaust was attached. Sounded sooooo much better with it closed. I can't remember, but I think I was over a hundred at one point.

X5 with headers - YouTube

Quote:

Originally Posted by bcredliner (Post 971117)

R rating 106mph 130km/h
S rating 112mph 170km/h
U rating 124mph 200km/h
H rating 130mph 210km/h
V rating 149mph 240km/h
W rating 168mph 270km/h
Y rating 186mph 300km/h

The tires are capable of higher speeds than the rating, however, BMW uses the minimum level for speed limitation.

Some aftermarket software, such as Dinan engine software that a few of us have, remove the speed limitations, otherwise speeds are limited by the chart numbers.

Worth noting here, ANY tire damage (tread/sidewall tear, puncture requiring patch/plug), will reduce the max speed rating of a tire AT LEAST one rating.

Some owners (myself included) will install tires 1 or 2 ratings higher then the OE set. I currently have W rated (168 mph) tires on my X.

The "peace of mind" from having "faster" tires then the vehicle is HUGE during the 2 miles of distance it takes to see the last few mph.

For those doing high speed runs, get a safety margin in your tires.