Short answer: You can leave the front wheels alone. Watch to make sure your back tires maintain the same overall diameter as you currently have.
Long answer: Unless you are mainly drag racing, I'd move up to 18x10 on the front and put 275s on. Match the tires if you're trying to keep the understeer/oversteer the same as now.
I have 18x10 and 19x11 rims (+1" from stock front and rear). 19x12 would be better, but I don't have a widebody. If you're really looking for better grip, consider putting 18" rims in the back. People who race or have serious power go with 18" on the back and step up to r compound tires