Because I like to over analyze things, I feel like there is more to what we see.
If we assume these are not numbers, then the structure of the letters leads us to believe the last "vertical line" is the spine to another letter. The first letter we see resembles an "R". The spine to that "R" only has a curve at the upper left of the spine. The next "letter" has a curve at the upper left AND at the lower right (and is slightly wider). This makes me think this is an "I". The second letter has the spine piece identical to the "R" making me believe it to be a "B" when combined with the next piece. The last piece is identical to the spines from the "R" and the "B". This means there is an additional piece that goes with that letter. This would limit it to a small number of letters (D, E, F, H, K, L, M, N, P, R - I left the B out of this list since the previous B extends below the spine and we would see it in range of view for the next letter).
However, these letters don't give us much in terms of word development if the "R" is the first letter. So that makes me think there is more before what we see.
If "RIB" is in the middle of a word you can come up with words like "TRIBE" and "BRIBE". These are the only consonants that make sense to me at the moment. I know Native American heritage is big in the Michigan area, but I wonder if there would be any "PC" issues with using something like "TRIBE" as part of a line of bowling balls.
Now that I have wasted this time, I guess I can become more productive on something more important.