The 17x8 Storm S1 in 4x100 +45mm in Goodwinracing.com shows 16.8 lbs and I know they weigh every size wheel they sell, the 4x108 will be the weight same or damn near it.
http://www.good-win-racing.com/Mazda-Performance-Part/61-1649.html
Also the wheel is significantly stronger being flow formed than a cast or heat treated cast wheel.
If one is worried about bad roads then stepping down to a 15 or 16" wheel is the best option no matter how good the wheels are made in 17, more sidewall with the right tires is going to ride better and take out a great deal of the load the wheel has to endure, doing so with lighter strong wheels will be even better.
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For those wanting 17's you must pick tires by actual specs, not by the generic sidewall numbers which can be very misleading.
Most wider tires are to tall for this car, another reason to switch to smaller diameter wheels but these will work well though spacers may be needed depending on camber settings.
Weights are rounded up or down, not specified in most cases but all things being considered saving weight that far out from the center is an important consideration.
Summer only super stick tires meaning they do not last long:
Bridgeston RE71R,
205/45/17 24.3" diameter which gains .5" sidewall from rim to ground compared to the stock tires, will help on bad roads
8.1 section width is good, 7.0 tread width is rather narrow, $143 in Tirerack
21 lbs, $143
Dunlop SS II,
205/45/17, 24.3" diameter as above
8.1 section, 7.6 tread width is better than above
20 lbs, $153
Dunlop SS II,
215/40/17, 23.8 diameter, .25 sidewall gain
8.6 section, 8.0 tread (as wide as I would put on an 8" rim)
22lbs, $162
Falken RT615K (I have no experience with these tires but the older version road like a brick and noisy, got greasy fast, these are supposed to be much better)
205/40/17, 23.4 diameter, close to stock so ride likely stiff, not as good over bad roads due to stiff sides and lower profile.
8.5 section, 7.2 tread, not that wide
20lbs, $126
RT615
215/40/17, 23.9 diameter which is better than above
8.7 section, 7.3 tread, barely wider
20lbs, same weight, $131, not sure why they made them so close to the 205/40/17 in actual specs
Federal RS-R
215/40/17, 23.7 diameter
8.7 section, 7.5 tread
22lbs, CHEAP to buy, very good things written about these tires for the price hard to beat I hear but I have never tried them.
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Best summer only longer lasting, fitment, etc...:
BFG Sport Comp 2
205/45/17, 24.3 diameter, good for bad roads
8.1 section, 7.8 tread which is a very good fit on an 8" rim
21lbs, $94, great price, longer lasting than the above and a very competent tire
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Best high performance AS tires which are really 3 season and what you want if you drive below 50 degrees in the rain and light snow, some summer only tires may even crack if to cold!
Mich PS A/S3+
205/45/17, 24.3 diameter
8.1 section, 6.8 tread (rather narrow but not always a bad thing in the snow, rain, cold)
22lbs, $152
(note, I ran this size in the none plus version, W or Y rated, road like a brick, very noisy, gave them to my daughter and went to 15s
they looked quite wide on 7" wheels and a bit more stretched than I liked on her 17x8 Enkei wheels)
Nitto NeoGen
Damn good AS tire for the money, what I now run in 205/50/15 on 15x8 6ul and love them, far nicer to drive on than the Mich I had on 17's and I am very impressed in the cold and wet on my car with a big turbo, tight suspension, etc)
205/40/17, 23.54" diameter so close to stock
8.5 section, tread width not listed but they run quite wide, the size I run above is perfect on an 8" rime
weight not listed but they are not super heavy. $80 each on Discounttiredirect
205/45/17, 24.33 diameter (best pick for bad roads)
8.23 section, width likely good on an 8
Weight likely not an issue, $94
215/40/17, 23.9" diameter (better than the 205/40 on bad roads)
8.86 section so likely nice wide tread but good on an 8" wheel
Weight should be a none issue, $97 each
I have not used the NeoGen in 17's but I would buy them over the Mich AS/3 if I ran 17's again, since selling the car I might put some on the 17x7 feathers I have since all my 15's are wanted by others here.
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These recommendations are based on looking at real specs and my real use or info from those that are actually in the business and have far more experience than us on the forums.
There are other lessor tires to pick from as well but not many that will do what these tires will do, if you need a more hard core AS tire as in more than a dusting of snow then others will likely suite your needs better or run dedicated winter wheels and tires.
Thousands of racers now run flow formed wheels instead of forged or cast for good reasons, cost to strength ratio, etc, there are some good heat treated cast wheels used by members here.
Hope this helps, I just spent an hour on it
Rick