Stock Maverick as in stock rims? If so, I have 245/60/14s on my stock rims... 75 Maverick too. If you are talking about biggest with any rim, then I suppose it all depends on exactly which rim, and which backspace. Couple guys have 275/60/15s... 7" and 8" rims. DHearne has 295/50/15s IIRC... He has a custom 9" rear that requires a deep backspace. Then there are some 275/50/15s and I believe CaptainComet has 265/60/15s. Someone else will have to chime in if you want info on rims larger than 15". Welcome!