Tire Question for UMP USMTS IMCA

[Dirt_Buster]

What tire out there is the softest and best for all around grip? We have an open comp race coming up and were only normally with IMCA tire which isn't the best one to go with and the tires on the late model which we can't tuck. So which one is out there that is the softest and provides the most grip wise for our 15x8s? TIA

[Lizardracing]

In my experiaces the AM fired a bit sooner and the speed didn't seem to fall off as quickly but the maximum grip offered didn't seem as high. The AR is also shorter with a tread face that's flatter.
They seem to squirm less and have better turn in feel. I prefer the feel of the AR's more on my car anyway but very few of my chassis are chasing USMTS/USRA. The brand does well with UMP however.