I have a WR147 with spiked tires but I really wanted to avoid drilling or using adhesive to attach a weight to the back.

I discovered that a 2.3lb dive-belt weight fits SNUGLY into the hand hold in the back. Basically you just jam it in, and it won't come out unless you pull with decent force. I added a zip tie so I can pull it out easier. The weight is far enough back that it acts as a counterbalance.

The weight I used is 2.3lb version: https://www.amazon.com/gp/product/B01M1HKYLE/