I've done a few searches on the topic but I haven't found and acceptable answer...

I'm planning on changing my stock 17" wheels/tires to aftermarket 18" wheels/tires. The wheels (4) are 18X8.5 +24 OS. Is there a problem with the two options below? The percentages (speedometer) shown are from the miata.net calculator if you deviate from the stock setup. I thinking of staying with the setup for the stock 18" tires but also considering other two options.

STOCK 17
225/50-17 F
235/50-17 R

STOCK 18
225/45-18 F (-0.4%)
245/45-18 R (-1.6%)

OPTION 1
235/45-18 F (-1.8%)
255/45-18 R (-3.0%)

OPTION 2
235/40-18 F (+1.8%)
265/40-18 R (-0.4%)

Any advice/help is appreciated. Thanks.

Norb

 

I just had a conversation over the phone with Lucius @ Discount Tire Direct (Luke had surgery) about another option:

245/40-18
275/40-18

The wheels that I was considering are the Enkei RZ-5:

18X8.5 +24
18X9.5 +25

Lucius seems to think that the offsets indicated above would make the tires stick out and not flush with the fender. What would be the correct offset for this setup so that it's flush with the fender?

Thanks for the help.