I just got some 17x9+45 rpf1s. I have a couple questions. 1 how big of a spacer can u use on stock studs an still be plenty safe? an 2, how can I get the center caps to fit in the rear? I'm running 245/40 all the way around too. Any advice would be heatedly appreciated. Thanks

 

5 mm spacer is more than enough for the stock studs.
If you're planning on fitting 9J et 45 on the front, they will rub no questions asked. You'll have to roll the fenders and maybe even pull them, as well as a lot of camber.
Center caps - what center caps are you using? Guessing they are not fitting because of the wheel center nut, you have to thin it out in the center.

You won't be able to fit spacers+rpf1s, especially with 9J et45 and 245 in the front. I will look like crap and will handle like one too.

 

For the rears I had to sand down the inside-center of the caps (a good amount ) until I was able to make them sit flush with the wheel, fronts she fit no problem for the caps

 

Both front an rear fenders an rolled an pulled a little. An I cut my rear bumper tab out an trimmed the front liner. I was running some grids,17x9+42, an they fit perfect. I just wanted to poke them out a little bit more that's why I was seeing if spacers would help an what would look clean. I'm getting my rpf1s Friday an just tryn to figure out what I want to do an if I want to stay with the same tire all around. I have 245/40 rite now.

 

 

Thanks! :-) I'll try that