Well, how much is too much? How long is a string, and a bad year?
Actually, BMW specifies a maximum weight, FWIW. On my K13 the numbers are 80g for each wheel.
I also do the tire change and balancing my self (dynabeads
We,(as in a friend of mine and yours truly) have been playing around with the balancing part. We tried to balance the rim only (before mounting tire) and I learned that my rim, with TPM actually needed 44g to be in balance.
With the rim in balance (the weights were taped on) we mounted the tire and now we were able to find and mark the heavy spot on the tire.
Then we deflated the tire and rotated it on the rim to counterbalance the rim.
On the first attempt, this way we ended up with only 5g of weights. (meaning the tire was 39g out of balance)
Playing with numbers, this means that in worse case, we might have needed 83g of weights. This also means that the prescribed 1oz that Dynabeads prescribe for my bike would not be enough.
So now I always find the heaviest spot on tire and counterbalance the tire against the rim before adding the dynabeads.
Time consuming, but works great.