You don't need radials, nor a manual trans to get good chassis dyno results. We dyno big tire drag cars all the time. All you need to do is put plenty of air in them, so it doesn't crush the tire and chunk it. Other than that it is a non issue.

The "inertia" dyno thing is just something guys toss around who don't know how to set their dyno's up for power. You can "lie" to a chassis dyno. All you are trying to do is control the rate of acceleration. So if you tell the dyno that the car weighs 4000lbs, when it really only weighs 3000lbs, you will get more control. Many ways to do it.

As far as the power numbers it spits out........I could care less. I am TUNING, not trying to get a sheet to brag to my buddies about. If I make a change and the power increases, we went the right way, no matter what the total output number is. That is really just a meaningless number