Once I glue my tires or open a new pack of pre mounts, I'll throw them on my car, start it and give it a few good revs, that way all 4 tires can balloon a bit and let the foams settle. I will then balance every tire regardless of premount or if i've glued them. Wheels/tires out of balance will reduce straight line speed and reduce grip. You'll be faster with balanced tires, regardless, it makes the vehicle feel much better and allows you to concentrate on driving. I also wont use proline foams any more. They just change shape with a little moisture and loose all consistancy where the AKA ones stay consistant and good. Dont get me wrong, I like proline tires, its just the foams are the issue. I also reuse my black AKA foams as they are usually good for 3 sets of tires before they go off. AKA's new red foams however I do not re use, they are far better than the blacks but because they are shaped differently and are softer, I dont think they last as long. As a general rule of thumb, I use AKA these day as the local hobby shop who helps me generally sells AKA.