I got them from tirerack.com They were the only place that had them. I even called Bridgestone USA to see if there was a local tire dealer that could get them. They said they were not even avalible in the USA. This was in 2003. Maybe things have changed.
mow is right...you *could* even go with 205's all around and become a member of the club (Spyderchat joke).
Try your best to maintain a stagger (wider rear, narrower front) or you'll be somewhat more prone to oversteer at/near the limits of the car. You may say that you never drive your Spyder near the limits on the street and that's fine...until a little Mexican death rat dog steps out in front of you and you decide to spare its life by doing an emergency lane change and back on a sweeper. You'll find the limits real quick that way.
You should be able to find the stock Bridgestones, Yokos, or Pole Position SO-3's (all well recommended) in the proper sizes.
if you want to get some tires locally, you can check out discount tire/america's tire company. it's not so bad there....or there's this small shop in baldwin park (626) called perez tires. i usually get my tires thru them.
Go with Discount/Americas tire company...good selection of tires and rims great service and excellent warranty's. Great prices on rims, tires and packages, or wait until they have their annual warehouse clearance sale...killer prices and you can negotiate the price. I have Nittos on the 00, Goodrich on the 87, Kumos on the Honda Si, Goodyears on the 94 Vette. If they don't have what you want they will order them.
I tried the 205-50-15 Azenis I had on the MKI on the spyder with a set of 11 lb 15" wheels and it handled excellently. A tad more oversteer at the limit, but nothing I found uncontrollable. Actually Id say for a competition setup its probably better. YMMV. Of course, then I got a good deal on a pair of 18" and a pair of 17" wheels, and now Im pimpin bling bling style. hahaha
I now have 2003 spyder rims for my 89 Mark I and plan on buying some Falcon Ziex 512's from Discount tire but if they aren't available there you can order some from www.vulcantire.com sometimes its better one way then the other. Those are the cheapest for decent quality I have found as long as your not racing ALL the time just your occasional mex-rat-dog. You are right its hard to find matching sets with sizes you want for the spyders 2003+.
But they sure look nice on a Mark I. :evillaugh