Easier methods :
Tamiya 1/10 off road tires, they are using the same wheel hex like FW-05T. Consider the wheel and tires from Tamiya Dark Impact buggy.
Tamiya 1/10 off road shock dampers. They are made from light blue alluminium, and have longer body to properly absorb roughness.
That's the easiest method to make a rally car.
Check tower hobbies for the parts.
Harder methods ( crazier & waste of $$$ ) :
Perhaps if you are adventurous person, you could experiments with longer suspension arms from Team Associate B4 buggy or Team Losi Kinwald buggy, that could fit into FW-05T.
You are going to buy the whole unit of B4 suspension arms, and plant it into FW-05T. You also need B4 rims and tires.
On Road : Xray NT1 , RX8 , T4 || Mugen Seiki MRX4-R , MTX4 , MTX3 prospec || Tamiya M03 , M04 || Top Racing Sabre FD2
Off Road : Xray XT8 || Hobao Hyper 8
Radio : Futaba 3PKS || KO propo EX-10 eurus