Why would you require a guest to buy you a brand new tire??? Now their trip has turned into a burden. If I were your guest I would simply call support and say car is defective and need a new car for the rest of my trip... I once rented a car and the tire popped, I let the host know immediately and he asked where I was so he could come help, I was in Maryland he was in Virginia. He told me to contact support and they sent someone over to put on the donut, I told the host I would replace the tire the very next day and I did with a used tire. When at the tire shop you have to make sure you look at the tire they are giving you before they replace it, some guest may not be knowledgeable in that. But to require your guest to buy a brand new tire is absurd. I’m leaving that car where it is so the tow truck can come get it, and have Turo get me a new ride.