My Cooper STT Pro’s are a C load. The Discount Tire I bought them from balanced them perfect within 20 minutes. I told them before hand that if they weren’t perfect I’d be right back. I was very insistent on everything I wanted and stood over the guy at the computer as he typed in everything I said; short valve stem, 95 ft/lb torque, 26psi, weights on the inside. When the finished I took them for a spin immediately. Got up to 65 and it was smoother than before with my 31’s that always had a shimmy between 45-50mph. That has been gone and remains gone now 2 months later. I think it’s the guy behind the Roadforce Machine. That makes all the difference in the world. And my upfront insistence that I will be back as many times as it takes to get this right. They have appointments every 30 minutes, so they don’t want to screw up. They actually screwed up my wife’s vehicle that day by putting the weights on the outside of the rim. I made them fix it. The manager actually came out and said, “We’ll move them inside, but I just want you to know that these Yukon’s are notorious for not balancing well with weights inside, so if you have a problem, just come back and we’ll put them outside.” So, that’s my experience. I’ll tell you one thing. This Discount is the nearest one to us, 50 minutes, but I’d never ever go to the two shops in our town. I’ve been multiple times and never got a perfect balance. Moral of the story is, find a good shop that does good work and don’t settle for less