I've got a set of 16x7.5 Kosei K1s, and am trying to figure out whether to make them my daily drivers or my autocross / track wheels. It's totally dependent on how easily I can fit 225/50/16 r-compounds. Typical 1" drop. The wheels are 16x7.5 with a +43 offset. I'm assuming there would be some trimming involved. How much? TIA.

 

Ideally if you go wider on the rims than stock you want less offset for more clearance but keep tire diameter smaller than stock.

16x6.5 with +48mm offset is stock
16x7.5 with +43mm offset puts your rim edge a little closer to the inside of the wheel well about 0.25". This leaves less room if you use a wider tire.

225/50-16 is a large tire, wider and taller than stock.
It fits rims 6-8" wide, perfect fit for 7" rim and tire diameter is 24.9" or about 1/2" taller than stock and 30 mm wider than stock. They are also heavy about 24 to 27 lbs each depending on which tire.

Odds are you going to get some rubbing maybe both front and back so be prepared to do trimming of the liners and maybe even spacers 3mm or 5mm if you hit suspension parts like the shock body in the front or lower rear trailing arm in the rear.

Another option is to go with a different tire size like 205/50-16 (fits 5.5-7.5" rims) if for street use vs

For R compounds
215/40-16 Kumho V710 fits 7-8.5" wide rims, perfect for 7.5" rim, 22.6" tire diameter, 19 lbs
205/45-16 Hoosier A6/R6 fits 6-8" wide rims, perfect for 7" rim, 22.8" tire diameter, 19 lbs, (225/50-16 possible)

 

Thanks for the post, Minihune. I'm just wondering how much trimming is involved. I'm only willing to go so far, and would like to find out before buying the tires! Or I wish more options were available at 225 with shorter sidewalls. The 215/40 Kumho V710 diameter is appealing, but I'd really like to cram 225 on. My other option would be to use these as dailies and get some 15"s for the r-comps... Which is probably what I'll end up doing......

 

The bigger wider the tire the more you have to trim. It's not very fun to trim stuff.

215/40-16 is a good size even if it doesn't seem that wide. What helps is that the rim itself is wider than stock.

Cramming wide tires on a wide rim isn't always a good strategy.

If 16" wheels are for daily street use then use 205/50-16 tires.

15x7 or 15x8 rims will work with 205/50-15 (V710 or Hoosiers), 225/45-15 (Hoosiers) or 225/50-15 tires (V710s).

15x7 with +38mm offset will give no rubbing.
15x8 with +36mm offset will give no rubbing in front but slight rubbing on the rear trailing arm in the rear- use 3mm spacer and it's fine.

This works with stock MINI brake calipers and even with JCW calipers but always check the clearance when using 15 or 16" wheels.