What is your SSEi reving when it goes through the traps in 2nd gear? Even with the tall tires, that seems wierd to me.
I agree that you don't want to go to a 22 or 24" tall tire, as it will cause you to use a bit of 3rd gear, not most of it like you said, but some of it. IMHO 26" tall tires is just about perfect for these cars at the track. A 16" rim won't weigh too much, especially if you get a lightweight aluminum wheel, and it should definately be lighter than the stock 17" wheels that come factory. I'm not even sure that a 15" wheel will fit over the large front brakes on the SSEi, so I think I would definately go with a 16" wheel. Your car is going to be faster if you can continue to have it only use first and 2nd and not shift to 3rd, so maybe you want to go with a tire the same height or maybe taller. Once you get to the point of shifting into 3rd gear, you are going to have to be making power to get through that gear to gain much since it is SOOO long. I don't know how serious you want to get, so I really don't know what to recommend. So let me ask you, how serious do you plan on getting with your SSEi?
1990 Maroon Grand Prix STE McLaren 3.1 Intercooled Turbo, 14.695 @ 94.49 on 12psi before cam/heads/etc.
1990 Bright Red Grand Prix McLaren 3.1 Intercooled Turbo, 14.819 @ 92.72, 189whp
1999 Grand Prix GT 9.75:1|K&N|160 tstat|No Ubend/Cat/Res|UD Pulleys|Ported M90/TB/Heads|XPZ|2.55"|Pacesetters|Stage 2 I/C. 12.442 @ 112.78
2000 Blue Bonneville SSEi Supercharged Gutted Airbox|K&N|3.4"|1.9'*|WP Pulley|Custom DHP|180*stat|41932'*|No Cat. 14.681 @ 94.80
2002 Dark Cherry Grand Prix GTP Supercharged & Intercooled
12.084 @ 114.38 w/1.743 60', 315.6whp, Fastest Stock Cam M90 GTP!
NOW XP CAMMED, 340.6whp with XP, stock heads, Gen 3 M90, 11.984 @ 115.84 w/1.750 60'!
Most HP Stock Heads Gen 3 M90 GTP!
2004 Red Monte SS Supercharged K&N|3.4 Pulley|1.9'*|180*stat|41919 plugs|3" dp|No cat/ubend|DHP|Shift Kit. 14.2 @ 98
GOT BOOST??? Friends dont let friends drive stock!