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Hey everyone, this is my first post so please be patient. I've been reading up a lot the volvo s40 and I definetly plan to buy one next summer, but I've been forming all sorts of plans for aftermarket mods. My basic goal is increasing performance, looks also but not at the expense of performance. <p>A stage 3 upgrade is a given, but its unsprung weight and rotational mass where a lot of performance can be gained. From doing some research I found that if you double the diameter of the wheel, you quadrupal the rotational mass; and if you decrease the weight by half, you halve the rotational mass. So I don't need huge rims, I mean if 18+ were better performance why wouldn't sti's and evo's use them.<p>Basically, with price not being a concern, I decided 17'' lightweight rims is the best option with 225/45 tires with an 8'' diameter...I think that will work, someone correct me if I'm wrong. In how much the rims weigh I'm looking at less than 22 pounds. And in terms of looks, I like the mult-spoke look that the evolve e7 rims look. Now with all that said, does anyone have any suggestions?<p>As for brakes, I haven't done any research, does anyone have any input in that area in terms of decreasing weight while improving performance?<p>Any other input toward this topic is appreciated too. Thanks all, and sorry for the length of the post.<p>Silas
 

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Re: Reducing unsprung weight and rotational mass: wheels and brakes (elros)

elros,<p>I'm a swedespeed normal guy, only knowing what I've learned from reading and a bit of doing. So I'm not an expert.<p>I was in exactly the same boat and had the same conclusion - that 17 inches might be the optimal size considering performance ONLY. Performance here means not only steering and road feel (18 inches might win there), but also acceleration, deceleration, steering at super high speeds, pot hole damage risk, etc. Also you're right - the Evo has 17x8 wheels with 235/45/17 tires (actually MORE sidewall the S40 stock 205/50/17).<p>18 inches might also be a good performance sweetspot, but I think most available wheels from the usual sources (Heico for example), while being strong and looking good, are too heavy. The stock 17x7 wheels on S40 are about 22 pounds. There are some pretty lightweight 18x8 wheels on tirerack.com if you want to go that route. <p>S40 wheel offset is 52.5 mm.<p>I was hoping to find a 17x8 wheel for 225/45/17 tires. I hoped to find something close to the 52.5 mm offset.<p><br>I found stuff close, but not perfect.<p>Ronal R41: 17x8, 22 pounds or so, 42 mm offset (not lighter, offset too far for my personal bias to try to stay close to 52.5, although people do use offsets as low as 40 or even lower with spacers)<p>Volvo's own 17x8 Pegasus: 46 mm offset (good), 27 pounds (bad). Looks really cool!<p>Evolve's R5: 17x7.5, 42 mm offset, 18 pounds. Pretty nice wheel. Available only in graphite or black. 42 mm offset again a bit too far.<p>Shuk W22 17x7.5 from tirerack.com, 18.5 pounds, 45 mm offset. It is ia two-piece wheel with outer rim forged (stronger, lighter). That's what I purchased, along with 225/45/17 tires. Even at 45 mm offset I can detect slight steering geometry changes, although nothing really problematic. Overall, I'm really happy. <p><br>If I had to do it again, I might try<br><A HREF="http://www.teamdynamicsracing.com/" TARGET="_blank">http://www.teamdynamicsracing.com/</A><br>because they can make 17x8 with the exactly right bore diameter (so no hubcentric ring needed) and offset of 48 or even 52 mm, and pretty lightweight for reasonable price.<p>Note that 225/45/17 is best suited for 17x7.5. Then again, 205/50/17 is best suited for 17x6.5, but Volvo chose to put it on 17x7.<p><br>Again, you can search on the S40/V50 forum for more info.<p>Hope this helps!<p>Bassman<br>
 

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Re: Reducing unsprung weight and rotational mass: wheels and brakes (bassman)

Articles on the offset subject post the fact that the offset should not vary by more than 5 mm! <IMG NAME="icon" SRC="http://********************/smile/emcocktl.gif" BORDER="0">
 

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Re: Reducing unsprung weight and rotational mass: wheels and brakes (jone)

Yep, that is definitely one of the datapoints. I'm happy with the performance I have at 7.5 mm shift, and believe (maybe wrongly) that I'm not doing untold damage. But as I said, if I did it again, I might get a custom made wheel with 48 mm offset or even 52 mm, 17x8 (maybe 17x7.5, not sure), correct bore hole size to avoid hubcentric rings.<p>By the way, hubcentric rings are not a big deal if you purchase from tirerack or some other similar place. They will supply the right hardware with the wheel, including hubcentric ring and new bolts for proper fitment to your particular car.<p>I should add that in my case, I have no rubbing at all. With 17x8 and a custom made wheel with 52 mm offset and 225/45/17 tires, there MIGHT be rubbing, although it seemed to me like there was some room.<p>
 
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