Having recently run into Clearance Issues after I Lowered my MCS(R56) on Coil-Overs, I came across this Offset Calculator.
^ the link is: http://www.1010tires.com/Tools/Wheel-Offset-Calculator#Results
Note: IF you are also changing WHEEL WIDTH, you need to figure 1/2 the width difference into your calculations: (Offset measured from the Center of the Wheel, so = 1/2 difference)


~ After Searching Out & Reading most of the posts on "will these fit", "what size spacer" and "Will It Rub"; then buying 15mm spacers for my 17x7 +42 wheels with 205x45's Only to discover my front Coil-Over Clearance Issue to be converted to Tire-to-Fender Rub... the calculator saved time & headaches.

Just in case you are wondering; Spacers Lower the Offset of a wheel, (e.g. +42 add 15mm spacer equals +27 offset. Or put another way: Your now +27 offset,(42-15), will move your wheels outward 15mm toward your fenders compared to the +42 offset.

It all seems 'easy-obvious' once figured out; but doing the calculations for each wheel was non-Fun. Using the calculator, I figured out exactly what would fit & then found another set of wheels.

p.s. just f.y.i. A weeks search + Calling Enkei result: They stopped making the PRF1 17x7 in +30 {NONE in US or Japan}! Oz Leggenda is available in 17x7 +30, but I didn't like the look. ~ Ended up with Kosei K1 TS in +36 {I'll find out tomorrow if I still want 5mm spacers in front}

 

I like this site better: http://www.willtheyfit.com/

I'm also not sure I follow your story. Instead of switching out the 15mm spacers for 5mm or 10mm you bought a whole new set of wheels?

 

Thanks Creeve, I like 'willtheyfit' as well:: added to my favorites.

& Yes, you follow; Yet - Another Set of New wheels! {instead of different spacers}. for a few reasons:

• Lighter wheels @ 15lb
• Fixed offset /Clearance issues (without Spacers)
• made new Huf-Beru TPMS install Much easier* .
  • New Rs-Technik TPMS Stopped Transmitting inside of 5-Months of being installed!!!