I run 245-35 on the front with a spacer and have no issues but I think a 255 would have issues.
Is that on the stock rims? That's about as wide as I thought without rubbing. That 20MM would almost make up the extra inch of width on the Mandrus rims.
Stock rims:
Front 7.5x18 ET +35mm 225/40-18
Rear 9x19 ET +22mm 255/35-19
Mandrus rims
18x8.5 ET +32mm
19x9.5 ET +25mm