datsunlover Posted August 3, 2005 Share Posted August 3, 2005 To add a few more cent's here.. Last year I was running the 14" 6 spoke Z rims, and this year I run some aftermarket 16" wheels. They felt about the same (a bit lighter maybe) as the old 14's, but I did notice it takes a bit more effort to stop than last year. The thing is, the cornering and overall handleing is VASTLY improved over last year with the slightly wider and lower profile tire I run now, so I am willing to trade a little braking for that. I wouldn't want to go any bigger though.. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 3, 2005 Share Posted August 3, 2005 To add a few more cent's here.. Last year I was running the 14" 6 spoke Z rims, and this year I run some aftermarket 16" wheels. They felt about the same (a bit lighter maybe) as the old 14's, but I did notice it takes a bit more effort to stop than last year. The thing is, the cornering and overall handleing is VASTLY improved over last year with the slightly wider and lower profile tire I run now, so I am willing to trade a little braking for that. I wouldn't want to go any bigger though.. But see the problem with this comparison is that you went from a 75 series 14" tire to a 40 or 50 series tire. Of course there is going to be a lot less tire compliance which will make it feel a lot more connected to the road. What about a 45 or 50 series 14" tire? How would that have been in comparison do you think? The thing that I hear most as a reason for why it's OK to put huge tires on your car is that it makes the contact patch longer size for size. While this is true I don't think that it's always to your advantage to go with the larger rim. At some point the advantage of the bigger diameter tire is swallowed up by the disadvantage of having to accelerate, suspend, and brake that same tire. I suppose it doesn't matter as much if you have 400 hp and huge brakes, but even Scottie said his wheel choice was a mistake, and he isn't lacking power. My personal feeling, and it's just a feeling since I don't have any hard data, is that if you're talking Z's and your talking about handling, not just drag racing, your losing out when you go above 15", MAYBE 16". You can have the car lower with lower cg, the tires shorter for lower effective gear ratio, and you don't have to slam the car to get it to look right. The lever of the wheel to the hub is shorter, so the wheels don't have as much of a flywheel effect. I always wanted 13 x 10 slicks on my car, but that won't ever happen with my new brakes. Maybe on another Z someday... Quote Link to comment Share on other sites More sharing options...
Mikelly Posted August 3, 2005 Share Posted August 3, 2005 One of the reasons I bought some Marsh Racing Carbon Fiber/ Aluminum wheels years back was the unsprung weight issue... Steve and Ian up in Frezno ended up with them. They were 15X8 and weighed about 10# each. I read somewhere that 50# rotating mass was equal to a 100HP gain on road courses, because the benefits are everywhere it counts... Braking, corner speed, acceleration... I want to say the book was "How to setup you race car" but I no longer have the book and can't confirm where it was I read it... That chapter on rotating mass and unsprung weight helped me change a LOT of things in my program that helped me win an regional AutoX Combined modified/ Prepared group championship in 1995. Mike Quote Link to comment Share on other sites More sharing options...
johnc Posted August 3, 2005 Share Posted August 3, 2005 John are you referring to this article: http://www.grmotorsports.com/archiv...motorsports.com No. I searched their site and didn't find it. The article uses one of their project Miatas (the white one) for the test. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted August 4, 2005 Share Posted August 4, 2005 But see the problem with this comparison is that you went from a 75 series 14" tire to a 40 or 50 series tire. Of course there is going to be a lot less tire compliance which will make it feel a lot more connected to the road. What about a 45 or 50 series 14" tire? How would that have been in comparison do you think?... Actually, I didn't change the sidewall that much.. The 14"s I WAS runing, were actually quite small, 195/60/14 iirc (I know too small, it was all I had at the time, yada yada) Can you even GET a 45 series 14" tire? I've never seen one is all.. Anyhoo, I stood a 16" (205/50/16) rim up along side one of my old 14"s, and the 16 is a little taller too, but probly closer to the 'proper' tire hight.. I'm betting this has had an effect on the 'feel' of things too, as I have basicaly raised the effective gear ratio.. Quote Link to comment Share on other sites More sharing options...
Moridin Posted November 3, 2005 Share Posted November 3, 2005 Lighter wheels on a street car definitely help ride quality too. We did an imprompto test with two sets of wheels my friend had for his Volvo. One set weighed about 15 lbs per wheel more than the other (The heavier ones being and aftermarket wheel, while the lighter were off an 850R). The car rode much, much better with the lighter wheels even though they were of the 17" variety (compared to 16" for the heavier ones) and had a smaller sidewall. If I remember, they had the same tire (Nitto 555s). Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted November 3, 2005 Share Posted November 3, 2005 Just wondering how much weight a tire adds to the wheel approximately? for 15" by 225mm, 16" by 235mm, and 17" by 245mm just a ruff guess. Quote Link to comment Share on other sites More sharing options...
Moridin Posted November 3, 2005 Share Posted November 3, 2005 Sometimes the manufacturer will list weights on their website or tirerack will have it (mainly for "competition" tires though). I don't think they'll weigh much more by going up in wheel diameter (and down in sidewall size), but its the extra width that adds the mass. I have been known to be wrong before many, many times. Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 3, 2005 Share Posted November 3, 2005 On a recent BMI they tested 18 inch VS 19 inch setups and I think the 19 inch setups ended up being slightly larger in diameter and slightly heavier (like right around 1kg). The 19 inch setup was fast by about .3 of a second at sukuba, wich is a low minute track. It was just enough to make a small different in each turn (great side by side video comparison). To be fair though, the driver didn't feel much difference, and he's a pro driver, so that's saying alot. With aluminium rims I think weight increase is fairly minimised as you decrease the tire sidewall size. Another thing they talked about on the BMI is how rim manufactures are starting to make aluminium rims that flex better instead of cracking. Quote Link to comment Share on other sites More sharing options...
crazy280 Posted November 3, 2005 Share Posted November 3, 2005 I agree that lighter wheels/tires are almost always better. But something to consider is the "type" of wheel, rather than "just" the diameter. For example a forged magnesium wheel is almost always lighter than a cast steel wheel, even at larger diameters. Hypothetically you could go from steel 14's to forged mag 17's and actually lose weight. Also, many professional race cars have been very successfull with huge wheels, such as group 5 porsches back in the day with 19" diameter wheels (and that was back when 19" was totally unheard of). I'm not saying bigger is better, just saying that bigger is not "always" worse. It's something to consider Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.