You can run any tire you choose. But the wider it is, the happier you will be. I rode for three months through Europe on tubular tires, about 25mm or less. It was rough. I don't recommend it, but I did survive. I recommend going with the widest tire your bike can accept. You may not need to use as much pressure as you think. Experiment to find your ideal pressure. Excessive pressure can lead to extra fatigue in the rider. The wider the tire, the less pressure you need.