[Topless in Cali]

You can go as large as 19" rims with 235 tires, but you have to get the right offset for them not to rub on the inside or use spacers. I even read somewhere that 245 tires will work with the right rims, but that's really pushing it for the space and I would think some experimenting would be neccessary for a proper fit. There are some guys running air ride (big drop) and 19" rims. The rear has much more space and 20" rims will fit with 245 tires on the correct offset. You may even be able to go bigger on the rear if you really want a pronnouced rake in your PT. However you will probably have to special order a set of matching rims in 2 different sizes with matching tires in 2 sizes making it much more costly.