Tune must be unlocked?

Hi

Maybe this has been asked before. Have been running / are running Project Cars on Xbox one and iRacing on PC.
There are no limitations there what so ever how i can tune brake balance / dampers / springs etc …

But I can’t figure out how to do this in Forza 6. Please help me with the steps I need to take !

Also can I tweek “rented” cars ?
Must these tunes be unlocked for each car or if I unlock brake balance tune is it available in all my own cars.

//Regards KasbraLotus

The stock parts on most cars are not adjustable, just as most street cars in real life don’t have adjustable shocks, sway bars, brakes, etc. You will need to upgrade each car with “race” level parts to gain full tuning capabilities. Of course there are some cars, mostly race cars, that come with adjustable components by default.