You can try the on-line tire places, but locally I get them from a motorcycle dealer who sells them to me cheaper, and without a shipping charge.
bigger would be better, as I am not trying to wipe out on trolley tracks anymore
No matter the width of the tire, the contact area is about the same (very narrow), in an upright, riding condition. That "is the way" of tires for 2 wheel vehicles, it allows you to maintain tire contact when cornering, and is how your tire/vehicle is designed. If you are having trouble with railway/trolley tracks it is the way you are operating your 2 wheeled vehicle, not a tire "problem". "Bigger" may not fit within the confines of your fork/swingarm, so check carefully, tires are not a returnable item.