So I hadn't driven my A3 in a few weeks (waiting for snow to melt) and when I got back from a real quick trip to the store, I noticed after I parked my driver-side front tire had a pretty large (I'd say 1.5'' wide X .25'' deep) gash on the sidewall right under the rim lip . I have driven on it for over a week now and haven't noticed anything, or even air pressure loss... The gash is not straight in like a nail or screw would cause, it's sort of from the top and it was a slice, as opposed to a puncture. Kind of hard to describe, but I think it could be from ice rubbing against it when I parked it for the last storm we had.

My question is- is there an OTC rubber sealant I can buy and use to fill the gash to prevent it from wearing more? Or would this need to go to a quality tire and wheel repair place to check, and fix? Anyone know estimated cost(s)? The tire only has 4,200 miles on it THANKS!