I bought a set of FF15 HRE from Vidid Racing recently - size 19x8.5 +50 front and 19x11 +35 rear

What is the largest width tires I can run on these for my widebody C4S?

 

Interesting, Vivid Racing convinced me the 19X8.5 + 45 was the perfect size for a narrow body 997.2, yet sell you a + 50 for a wide body. Even though the fronts may be the same for both NB and WB, either mine is too wide or your isn't wide enough if mine are truly perfect as they contend. I think I saw guys running 51s + 15 mm spacers in the rear so your rears would seem to be about right.

 

on a 11j wheel i would not go anything more than a 305mm tyre. IMO a 295mm is perfect for 11j rim. As for the 8.5j fronts you can do 235 or 245mm max. any wider and it may cause that 'muffin top' look as the tyre will be too wide for the narrow rim.

 

After the edit to tires, yes . . . 305 and 245 work fine on those rims and no rubbing.

 

245s might be a little big for an 8.5" width and you also need to compare the rolling circumferences of the front and rear tire sizes you plan to run to make sure they're close or you can throw of the abs and PSM systems. You can google for a wheel width tire size chart that will give you recommended range along with absolute min and max.

 

With 4WD be caution on tires size as wrong size can have adverse results on the suspension.

Michelin Pilots are wider than other brand tires, IMO with your setup i would go 295R/235F (Michelin all the way). Have seen other folks ran 305 on 11" wide.

My car have 305/245 MPSS on 11.5"/8.5" HRE, no issue.