All of the GRP brand of 30mm tyres (fast, best, ellegi and so on) will rub on the hub carriers. Unfortunatly you cannot modify the hub carriers were the tyres rub because of the pivot ball placement.
I would like to see someone, Yokomo or another company, make some axles with a longer thread and also a wider aluminium hex hub so that these brands of 30mm tyre can be used.
But remember using the 30mm rear tyre will make your car push a little in the corners. Some miner set up change will be nessecary.
The 26mm tyre fits with no problems at all.