clint78z Posted October 2, 2001 Share Posted October 2, 2001 My friend Bill who I always chat with about tuning the DFI got his car in Hot Rod. He is a pretty much a genious when it comes to tuning and has a very scientific way of doing things. His car is extremely tasteful, and that intake, drool !! http://www.hotrod.com/editorial/article.jsp?viewtype=text&id=42798 [ October 02, 2001: Message edited by: clint78z ] Quote Link to comment Share on other sites More sharing options...
Guest scca Posted October 2, 2001 Share Posted October 2, 2001 very nice stang... i love 65-66 FB.... a timeless design.. like a Z.. and a 911. and a cobra.. now all it needs is much wider tires and rims. those factory rally wheels are nice but a bit narrow Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 2, 2001 Share Posted October 2, 2001 Beautiful car and setup! That's a great article BTW! Mike, I agree - I love the 65/66 fastback! And read his explanation (in the article) about his tire choices. Interesting reading! [ October 02, 2001: Message edited by: pparaska ] Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted October 3, 2001 Share Posted October 3, 2001 "And read his explanation (in the article) about his tire choices. Interesting reading! " yup, we had a long chat a while back on a 510 list quibbling on whether or not your actual contact patch was the same size REGARDLESS of your tire size assuming same weight of vehicle.........anyone care to take up that one Hmm, wonder how many mpg I'd gain with 195/70/14s again Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 3, 2001 Share Posted October 3, 2001 Beautiful car! That is a very good article. He has very clear reasoning, and I often wondered what the deal was with the wider tires. I took physics in high school and college, where they taught the friction force (ability to launch) is generated as a product of the frictional coefficient (tire compound) and the normal force (weight of the car). I always followed this reasoning, and saw most folks get wider tires to get better grip, which made no sense to me. If you increase the contact patch (wider tire), you spread the weight over a greater area, and the normal force is spread over a larger area, and goes down (per unit area). Therefore, in the theorectical sense, you gain nothing by going to a wider tire. The author claims a wider tire will slightly increase the frictional coefficient, which is evident in his data. Once again, I am sticking to my "sleeper" look, by not going crazy on tire width, and am sticking (pun, hehe) to quality compound tires. Quote Link to comment Share on other sites More sharing options...
clint78z Posted October 3, 2001 Author Share Posted October 3, 2001 Here is my understanding about tire sizes. Yes same wieght and pressure same contact area. Except that the wider tire has a wide contact patch, which will not deform in cornering as much. The wider tire is actually a softer compound in the same type of tire. For example a 235 Z rated tire is softer than the 205 Z rated tire. The bigger tire can handle the heat better, so they make it softer. The main advantage I am told is cornering since the wider patch resists tread deformation better. Quote Link to comment Share on other sites More sharing options...
Guest scca Posted October 3, 2001 Share Posted October 3, 2001 i confess that i havent read the article yet.... all i was going on was purely looks. i like the look of the tire filling the wheel well. could care less about frictional COEF...etc.. i understand the tire size thing a bit, from coming in to snow country .. you see IDIOTS with 4x4 and huge tires they have NO traction-- those that know have taller and narrower tires- a narrower/smaller tire is more PSI road contact thus more traction, but this doesnt apply when the tire compound is altered in dry weather. mud and sand are the opposite of snow. you want the car to float so you put wide tires on it. a race car on wider slicks has more contact patch but also more control. with wider slicks i can go faster than with narrower ones.. more rubber slows you down but more control in sliding thru the corners. more rubber in contact means more speed can be carried thru the arc of the corner. there must be some formula to determine this with speed and rubber compound and weather etc... off on a tangent...... Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 3, 2001 Share Posted October 3, 2001 Mike, I'm with you. Looks is important, but there IS something to wider rubber. If there wasn't, the race cars WOULD NOT be using it. Note that all the arguments in that article were for drag racing traction. Go around a corner and the wider tires DO help. Quote Link to comment Share on other sites More sharing options...
DemonZ Posted October 3, 2001 Share Posted October 3, 2001 I didnt' read the article, but my 2 cents on the traction thingie is... given a wider tire, and everything else equal (circumference, tire compound) the wider tire will usually handle better because it has more time to cool IF overheated, thus staying within it's operating temp. So for each revolution, the wide/short patch is in contact with the road for less time than a long/ narrow patch. Even though the area/contact patch is the same for both, the wide/short patch is spending less time overheating and that much more time cooling down. In adverse weather a skinny tire "cuts" deeper into the snow and rain increasing your chances of pavement contact. And if you don't scratch pavement, the skinny tire has more directional control because it cuts, whereas a wide tire spreads out the load like a snow shoe or ski and ends up hydroplaning or skiing rather than scratching the pavement or carving a path. If you're on ice with rubber, then I don't think it really matters DOH ! Ummm....anyways, that's my story Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 4, 2001 Share Posted October 4, 2001 We went over this a few days ago in my college physics class. If two different sized tires are on a car, but with the same pressure(pounds per sq. in remember), then the contact patch AREA is the same because the same amount of weight is being distributed through that tire. The thing that changes is the Shape of the contact patch, nothing more. the coefficient of friction is the same no matter the size of the tire, as long as it is the same rubber. A wider tire will dissipate heat more quickly though, due to a larger surface area exposed over the tire. Im getting off on a tangent, but the contact patches between the skinnier tire and wider tire are distinctly different. The skinny one is long and narrow, and the wide one is horizontal(width of the car). I can't explain it much beyond that, aside from the fact that the Force of Friction is just the normal force *'s the coefficient of friction. NO surface area stuff in there Quote Link to comment Share on other sites More sharing options...
blueovalz Posted October 4, 2001 Share Posted October 4, 2001 Thus from this you can calculate the tread contact by knowing the weight on each tire, and the pressure in that tire. In regards to the shape of the contact patch. Is there not some kind of reference material as to which axis of the patch provides the best "traction" in relation to that patch (wide for side forces, and narrow for fore/aft forces)? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 4, 2001 Share Posted October 4, 2001 I disagree with the idea the contact patch of the tire is the same for the same car (and same weight). A wider tire may indeed have a narrower patch front to back than a narrower tire, but just because the patch is differently shaped, doesn't make the surface area equal. Most tires have fairly rigid structures, slicks excepted, and just need to be properly sized to the vehicle to work optimally. Actually, I think the area point is moot, because the normal force (weight) obviously distributes through the entire contact patch (more or less). So any gain or loss in launch capability from a diffently sized tire is entirely due to the tire compound and how much weight per unit area you are putting on it - hence the increase or decrease of the frictional coefficient that affects launch capability. I know, I should just go to bed. 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.