If you aren't able to afford a new set of tires, consider purchasing a new BT-023/GT for the front. Then, replace the back with a BT-023/GT as needed. I got an extra 2.5K out of the rear BT-021 before it finally gave up. Purchasing tires separately splits up the cost, so it stings less. Also, the BT-023s are much better tires and should wear evenly compared to the BT-021s.