OK, this question is going to take someone who really knows suspension geometries and such.  I just got an e-mail from the tirerack with an update on wheels available for both my cars.  The project car being my '87 RX-7 Turbo II those are the wheels I am concerned with.  I have been eyeing SSR Competitions for quite some time now, due mainly to the weight of the wheels and the durability of the construction method used.  The tirerack's e-mail however had Gram Lights that were fairly comparible in weight and $160 cheaper per wheel.  Here are all the specifications listed on tirerack.com:

SSR Competitions 17x7.5 w/ 42mm offset 13.6 lbs ea.$389 ea.
Gram Lights 57c  16x7 w/ 42mm offset 15.0 lbs ea. $230 ea.

Obviously the Gram Lights are appealing for their price.  My handling question though is how is the increased size of the SSR's going to affect my handling, other than the increased tire section and less sidewall flex.  Keep in mind my RX-7 has manual steering too.  The Gram Lights are the stock size (I don't know about the stock offset) so they shouldn't affect the suspension geometry any.  Right now my suspension mods include Eibach Sport Springs (.8" lower ride height) KYB AGX shocks, and energy suspension suspension bushings all around.  When I get the wheels I plan on running BFGoodrich g-force TA KD or KDW's.  I have a second car so I'm not that concerned about all weather or rain capability.  I know this is a long one, but if anyone knows anything let me know.  Thanks!  

personally i run 16 inch tires on cars that are meant for the track, and so do a lot of people, overall you need the sidewall, a car will handle better if set up right on 16s over 17s but that's my opinion.  

I agree that suspension setup is more important than a difference in 1" in wheel diameter.  However, I would also be gaining a 1/2" in wheel width, which is putting more rubber on the road and thus generating an increase in overall traction.  My question though is will this increase in width, without a change in offset, throw off my suspension geometry and actually make handling worse or driving at the limit more difficult.  Apparently, as of yet no one is willing to tackle that question because of either lack of knowleadge (probable) or not wanting to sound like an idiot (doubtful).  Thanks for any input anyone wants to give though.  

As the RX is rear wheel drive, you will not get an increase in torque steer.. but you may get brake steer where the increased offset tries to jerk the wheel around under heavy braking on less than ideal surfaces. You might also get some tramlining.. where the wheels try to follow irregularities in the road.  

"My handling question though is how is the increased size of the SSR's going to affect my handling, other than the increased tire section and less sidewall flex."  -Matt

Your suspension is a constant in this equation, the only important variables being tire size, width, and tread pattern. Since you know the effects of the contact patch and sidewall flex and have chosen good tires (the KD being the best), there's not much else to tell.

"My question though is will this increase in width, without a change in offset, throw off my suspension geometry and actually make handling worse or driving at the limit more difficult."

It won't hurt your suspension performance. It probably won't make it noticeably better either, but it won't hurt. That fact is your current suspension is basic by most standards so splitting hairs and considering geometry over this is pretty useless. Now if you had adjustable coilovers, adjustable camber, then we can nitpick.

Now I don't know what your plans are for the car, but civicking also has a point. There are reasons why alot of road rally cars use 16's.

"Apparently, as of yet no one is willing to tackle that question because of either lack of knowleadge (probable) or not wanting to sound like an idiot (doubtful). "  -Matt

It's also a holiday weekend, and most of us have familes. Don't make assumptions. It's a fast ticket to getting flamed. Thanks, and post pics if you have 'em. We love to see the earlier RX-7's.  

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Apparently, as of yet no one is willing to tackle that question because of either lack of knowleadge (probable) or not wanting to sound like an idiot (doubtful).

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well the only problem is that i can get just as wide wheel that will fit the 16" as you can get for the 17" even though they are .5" wider. its not about wheel width its about tire width, but that's all to a point. with your current set up trying to choose between a 7" and a 7.5" width on the base that you will get better handling is not important, even if you had the best suspension setup the wheel be a little wider would not make much of a difference in handeling, the tire would. now seeing as there is a 1.4lbs difference in weight between the two you can argue that yes there is an advantage to that tire, but seeing that the price difference is so big for just a couple of pounds its not worth it. you could take that money saved on 4 wheels and get a coilover set up that would dramatically increase handling, way better then if you would have gone with the more expensive wheel, remember we have to be smart shoppers.  

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well the only problem is that i can get just as wide wheel that will fit the 16" as you can get for the 17" even though they are .5" wider. its not about wheel width its about tire width, but that's all to a point. with your current set up trying to choose between a 7" and a 7.5" width on the base that you will get better handling is not important, even if you had the best suspension setup the wheel be a little wider would not make much of a difference in handling, the tire would. now seeing as there is a 1.4lbs difference in weight between the two you can argue that yes there is an advantage to that tire, but seeing that the price difference is so big for just a couple of pounds its not worth it. you could take that money saved on 4 wheels and get a coilover set up that would dramatically increase handling, way better then if you would have gone with the more expensive wheel, remember we have to be smart shoppers.

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First off I apologize if I offended anyone with my previous post.  I'm stationed in Japan, I have no true friends here and my family isn't keeping in touch so I'm a little moody.  Don't be jealous because I am in Japan either, I've been here for a little less than six months and my unit still hasn't approved my SOFA license paperwork.
    As for the points addressed by everyone.  First I will discuss the weight.  True it is 1.4 lbs. saved per wheel, but remember I will have a lower profile tire also, which would be lighter as well if it wasn't for the extra half inch width.  I don't know how much of a weight savings this would provide for the wheel tire assembly.  Also as this would be a savings in rotational and unsprung weight the benefits should be greater than regular weight savings.  Lighter wheels, like a lighter flywheel are going to allow the car to accelerate a little quicker and brake better and less unsprung weight will allow the suspension to work better.  
    As for the cost yes the $159 savings per wheel is definatly tempting.  It would make for money for a coil over kit.  I did orginally plan on getting coilovers, but decided that I couldn't justify the cost because I was only going to set the height and forget it.  The biggest benefit of coilovers for me then is the ability to setup the corner weights.  So in the end I decided to go with the simpler and cheaper solution.  Maybe it could be looked at as I saved money on the suspension to spend on the wheels and tires, HAHA.  
    The biggest unfortunance of my asking this now is that my RX-7 is parked at my parent's house in the states, while I am here in Japan.  At least I may be able to pick up some needed parts cheaper while I am in Japan.  Thanks for the help that has been provided and again I am sorry if I offended anyone.  

Honestly Matt... best thing you can do for your car, find forum dedicated to it. As much knowledge as we may have here, there are perhaps only one or two people fully cognizant of the RX7.  

well you didn't really offend me, and your really not going to save any weight by loosing some of the sidewall because first that's the thinnest part of the tire, next most of the weight comes from the ply in the tire, is it a steel ply or are they all composite fabric? you will get a better unsprung weight savings by changing the brake rotors to a sports style with a removable hat, and changing to shocks to aluminum(coilovers), then you can change the control arms to the aluminum racing ones, that will really save you some weight. also change the calipers from all steel to aluminum, that is truly how you save weight in your situation, now if you picked a wheel that weighed 8lbs than yeah i would be all for it. also remember that rotational weight is not as much of a factor as is the extra width of the wheel because your increasing rolling resistance and increasing drag, these will have a greater impact on the car.  

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Don't be jealous because I am in Japan either,  

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