Firestone Firehawk Indy 500 top speed

I'm about to buy a set of Firestone Firehawk Indy 500s in 255/70/15 for my TA. They're rated S/T (118mph) I want to know how fast I can really go on them. My current crap Remmington (dont even know this dam company) tires that came with the car are also S rated (112mph) but I've definatly done over 130 in them a few times. So if anyone has any experience with them or has some insight into top speed on these please let me know.

Edit: if you know of tires in this size that are rated faster please let me know.

The Kumho Ecstsa STX KL12 is H-rated and is available in that size

Wow thanks a lot; the closest I've been able to find is a place that makes 275/60/15 H rated but it's on the west coast and only sells in stores.

I've been thinking and I'm gonna stick with the Firehawks because 1) I like the good snow traction 2) I need to curb my speeding
Thanks for all the help!