Hey guys,

I need some clarification, for my daily driven lowered RL

I currently have 18x8.5 +40 with 225/40/18s Kuhmo ecsta ast and 10mm spacers.

With the tires i have on now, i have a gap of about 20mm from the inside of the fender to the tires sidewall.

now if ive done the idiot elementary school math right, i could, in theory replace my spacers with 30mm spacers (not that i want to go extreme)
i would actually like to use 25mm spacers, but im not sure if a 5mm fender/sidewall gap is enough

A)what is the largest spacer size i can use on the stock lug bolts?
B)what size spacers would you recommend, and how much gap should I have?
C)What size spacers will require the extended lug bolts.
D)could i potentially run as low as a +10 offset version of my current wheels?