Ah, so that's why the tach was important! LOL.
I used to be around the corner in summerlin, just south of sun city. I worked at rainbow and 215 though on the south side. Wasn't too bad until the ikea went in, then traffic and congestion made life hell.. Even worse commuting through that with 3.91 gears and every yahoo doing 85mph. At least you're closer to the shooting range than I was.
Doesn't need to be freeway, but sustained speed at 45+ should give you an idea. Work up from there.
This is an ir temp gun similar to what I used and had good results with. Also handy for checking headers to check cylinder distribution or check for misfiring or stuck valves. Also means you can check brakes, rear end and trans pan temps really easy after a drive to see if anything abnormal is going on. Kids love to play with them too!