I was going out town this weekend and decided that I was going to push my 99 STS to the limit. I floored it and was only able to reach 129 MPH. I drove like this for about 40 sec and was not able to go any faster. Why was this?
I tell you what last time I ran down to ark city back in my days it took quite a time longer than it does in the old '79
The needle buries after 85 but I am pretty sure it does something like 130
That's an old fashioned governor... just run it wide open until it won't go any faster :=)
I had a '53 Sedan De Ville with a really funky intake manifold and carb that would do 120 all day long, but would never go any faster. Then I had a '69 Sedan that was the same way, but it was at about 125. I haven't had my 2001 STS any faster than 130, but then I haven't ried either. It came with "W" rated tires.
Just because a car comes with speed rated tires doesn't mean the car will go as fast as the tires are rated. Tires don't make speed. All the tire speed rating means is that Cadillac put those tires on that particular car because of the (or lack of) speed limiter.
My Olds Aurora came with "V" rated tires and it was speed limited at 139. I could never get it faster than 135. I put "H" rated tires on it because they were cheaper and lasted longer than "V" rated. When the Pirelli's wear out on the STS, I might go with a much slower rating than "W" because I'm not racing the ol' girl and I can save money with lower rated tires.