Its funny, when people talk wheels, the subject of weight almost always comes up, but when it comes to tires, weight is rarely mentioned.
From looking over many tire data sheets, the Toyo Proxes T1-S seems to be lighter than average for any given size. The T1-S in the 205/50ZR16 size is less than 20lbs, were as most other max performance tires I've seen in that size are in the 22-24lbs range. Saving 2lbs (per tire) may not seem like alot, but there are many who have spent big bucks to get that same 2lbs weight savings with new wheels. Plus, with the stock '98-'99 five spoke RS wheels weighting in at about 16.5lbs, there are not many 16X7 wheels with 53mm offset that weigh 2lbs less.
As far as unsprung weight goes, it doesn't make much of difference where the weight is saved. But looking at the tire/wheel combo as a flywheel, 2lbs from the tire is more significant than 2lbs from the wheel.
[This message has been edited by Scottie (edited March 28, 2001).]