Removed Posted September 6, 2006 Share Posted September 6, 2006 so you 2 guys are saying that a wider tyre has less grip than a narrower tyre. practical example : a 245 tyre is grippier than a 275? just wondering why the F1 cars don't run on bicycle tyres then Quote Link to comment Share on other sites More sharing options...
Digsy Posted September 6, 2006 Share Posted September 6, 2006 Bridgestones are still cr@p That's f@cking priceless mate after all this scientific banter! scientific Well it is to a numpty like me! Quote Link to comment Share on other sites More sharing options...
Dash Posted September 6, 2006 Share Posted September 6, 2006 practical example : a 245 tyre is grippier than a 275? just wondering why the F1 cars don't run on bicycle tyres then Not in dry but it the wet it actually can be, hence why wet tyres on race cars can be narrower, ever seen snow tyres on a rally car, why do you think they are so thin? : To place the pressure on a narrower area to improve grip levels. so you 2 guys are saying that a wider tyre has less grip than a narrower tyre. In the wet yes, see above. We are saying that the contact patch DOES NOT change, irrespective of tyre width, nor does the surface area load placed on that contact patch. See Below. We never said "a wider tyre has less grip" we said that a wider tyre has an equal load on its contact patch and that the contact patch remains the same size. However the wider a tyre is in the wet the more prone it is to aquaplaning or slip angles. Fat or thin? The question of contact patches and grip. If there's one question guaranteed to promote argument and counter argument, it's this : do wide tyres give me better grip? Fat tyres look good. In fact they look stonkingly good. In the dry they are mercilessly full of grip. In the wet, you might want to make sure your insurance is paid up, especially if you're in a rear-wheel-drive car. Contrary to what you might think (and to what I used to think), bigger contact patch does not necessarily mean increased grip. Better yet, fatter tyres do not mean bigger contact patch. Confused? Check it out: Pressure=weight/area. That's about as simple a physics equation as you can get. For the general case of most car tyres travelling on a road, it works pretty well. Let me explain. Let's say you've got some regular tyres, as supplied with your car. They're inflated to 30psi and your car weighs 1500Kg. Roughly speaking, each tyre is taking about a quarter of your car's weight - in this case 375Kg. In metric, 30psi is about 2.11Kg/cm². By that formula, the area of your contact patch is going to be roughly 375 / 2.11 = 177.7cm² (weight divided by pressure) Let's say your standard tyres are 185/65R14 - a good middle-ground, factory-fit tyre. That means the tread width is 18.5cm side to side. So your contact patch with all these variables is going to be about 177.7cm² / 18.5, which is 9.8cm. Your contact patch is a rectangle 18.5cm across the width of the tyre by 9.8cm front-to-back where it sits 'flat' on the road. Still with me? Great. You've taken your car to the tyre dealer and with the help of my tyre calculator, figured out that you can get some swanky 225/50R15 tyres. You polish up the 15inch rims, get the tyres fitted and drive off. Let's look at the equation again. The weight of your car bearing down on the wheels hasn't changed. The PSI in the tyres is going to be about the same. If those two variables haven't changed, then your contact patch is still going to be the same : 177.7cm² However you now have wider tyres - the tread width is now 22.5cm instead of 18.5cm. The same contact patch but with wider tyres means a narrower contact area front-to-back. In this example, it becomes 177.7cm² / 22.5, which is 7.8cm. Imagine driving on to a glass road and looking up underneath your tyres. The narrower tyre has a longer, thinner contact patch. The fatter tyre has a shorter, wider contact patch, but the area is the same on both. And there is your 'eureka' moment. Overall, the area of your contact patch has remained more or less the same. But by putting wider tyres on, the shape of the contact patch has changed. Actually, the contact patch is really a squashed oval rather than a rectangle, but for the sake of simplicity on this site, I've illustrated it as a rectangle - it makes the concept a little easier to understand. So has the penny dropped? I'll assume it has. So now you understand that it makes no difference to the contact patch, this leads us on nicely to the sticky topic of grip. http://www.carbibles.com/tyre_bible.html Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted September 6, 2006 Share Posted September 6, 2006 Quote Link to comment Share on other sites More sharing options...
Dash Posted September 6, 2006 Share Posted September 6, 2006 Thats what I was saying last night but it being late I think it may have become lost in translation. Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted September 6, 2006 Share Posted September 6, 2006 I pride myself in my responses being unintelligible Quote Link to comment Share on other sites More sharing options...
lomoto Posted September 6, 2006 Share Posted September 6, 2006 Bridgestones still cr@p though Quote Link to comment Share on other sites More sharing options...
Dash Posted September 6, 2006 Share Posted September 6, 2006 My Fastest Lap on the Nurburgring was achieved using a set of bridgestones. I was quite impressed by the grip levels and how nicely they kept the air temp and thus the pressure of the tyre. Food for thought. Here's hoping I can pull a few more seconds off y time with a "better" set of tyres then. Quote Link to comment Share on other sites More sharing options...
lomoto Posted September 6, 2006 Share Posted September 6, 2006 My Fastest Lap on the Nurburgring was achieved using a set of bridgestones. I was quite impressed by the grip levels and how nicely they kept the air temp and thus the pressure of the tyre. Food for thought. Here's hoping I can pull a few more seconds off y time with a "better" set of tyres then. Bet it was a warm day when you did it Quote Link to comment Share on other sites More sharing options...
Dash Posted September 6, 2006 Share Posted September 6, 2006 It wasnt raining thats for sure. But Like I said they are a summer tyre. Quote Link to comment Share on other sites More sharing options...
lomoto Posted September 6, 2006 Share Posted September 6, 2006 It wasnt raining thats for sure. But Like I said they are a summer tyre. Quote Link to comment Share on other sites More sharing options...
kennyc Posted September 6, 2006 Author Share Posted September 6, 2006 Ok we all know they are a summer tyre, it also rains in the summer. All I'm saying is they're not very good in the wet (crackin tyre website by the way Dash ) Quote Link to comment Share on other sites More sharing options...
mugwump Posted September 6, 2006 Share Posted September 6, 2006 At risk of getting flamed by everyone, traction control is not a magic bullet, it cannot defy the laws of physics, it is there to give you some safety margin when you *approach* the limit. Go significantly beyond it and I dont care how good it is its not going to save you, especially if the inputs from the driver actually are working counter to it (I am refering to steering inputs). Face up to reality, you bought a high performance sports car because you wanted to enjoy the speed and thrill of it. When its raining/cold/snowing/icy you need to treat it with respect NO MATTER WHAT TYRES YOU HAVE! I accept that you will find some tyres are better in the wet than others but they all have their limits. Having a better wet tyre might just instill a higher level of confidence in you that your car will grip and as a result you may drive at a higher speed, the resulting accident when it happens may also be significantly worse. My previous car (an audi) had 4wd, this equates to fantastic traction in snowy/icy conditions and I could pull away from anything with only 2 driven wheels, but hit the brakes and suddenly we are all on a level playing field because I couldnt stop quicker than anyone else...... The guy on here that crunched his door in was lucky, yes, if he had better tyres the accident may not have happened, but next time he might try the same manouver at a higher speed and it might not only be his door in need of repair. I dont wish anyone to not have fun in their car, hell I certainly do, but I have had enough near misses (one even on its roof in my mispent youth) to know that its futile to blame your tyres, car, traction control, the other guy, the conditions, whatever. The only person responsible for your accident is YOU! If the conditions dont allow it, make allowances...... but as lomoto says. Bridgestones are cr@p in the wet but drive like they are!!!!!! Rant over, flame me now.... Quote Link to comment Share on other sites More sharing options...
kennyc Posted September 6, 2006 Author Share Posted September 6, 2006 I think you need to re-read the post. The point I was making was that I was far from what I would consider the limits to be on a performance car that should have handled better and could that be (partly) attributed to the @*!# tyres. Having read many posts on the re040's it seems that they really are not good in the wet and that there are far better options out there. This is not the first performance car I've owned or driven, I'm not wet behind the ears...so to speak! And I'm certainly not relying on TC when I drive, it's mostly switched off Quote Link to comment Share on other sites More sharing options...
mugwump Posted September 6, 2006 Share Posted September 6, 2006 Hi Kennyc, I have read this post from the start, and I am not suggesting that anyone does not know or understand the limits of their car. Nor am I suggesting that you do not know how to drive a performance car. and as I said in the post above, yes different tyres will offer different performance in different conditions, but knowing the limits of the tyres you are on in the conditions in which you are driving is the difference between having fun and having an accident. We have all been *surprised* at times by the unexpected level of grip (or not), be it the result of diesel on a roundabout or whatever. I would just hate to think that anyone on here purchased a new set of tyres and thought that suddenly they were the solution to all their grip problems. I am losing count of the number of crunched Zed's coming up for auction on ebay as testement to the fact that this is a seriously quick car that can catch an awful lot of people out. If you drive a zed, in the rain, even on Bridgestone in the same way you would a micra I defy anyone to have an accident, my point is that you dont, because you bought a performance car and thats how you drive it. not getting at you, just take care...... Quote Link to comment Share on other sites More sharing options...
mugwump Posted September 6, 2006 Share Posted September 6, 2006 Oh dear, clearly I hve upset everyone now, at least 15 people have read this thread since I posted and now nobody is replying..... Quote Link to comment Share on other sites More sharing options...
Digsy Posted September 6, 2006 Share Posted September 6, 2006 Oh dear, clearly I hve upset everyone now, at least 15 people have read this thread since I posted and now nobody is replying..... Don't get paranoid, lad! I've just got nothing interesting or informative to say on the subject. Quote Link to comment Share on other sites More sharing options...
mugwump Posted September 6, 2006 Share Posted September 6, 2006 I've just got nothing interesting or informative to say on the subject. Me neither, but it doesnt stop me having a go... Quote Link to comment Share on other sites More sharing options...
Digsy Posted September 6, 2006 Share Posted September 6, 2006 I've just got nothing interesting or informative to say on the subject. Me neither, but it doesnt stop me having a go... Quote Link to comment Share on other sites More sharing options...
Sarnie Posted September 6, 2006 Share Posted September 6, 2006 Oh dear, clearly I hve upset everyone now, at least 15 people have read this thread since I posted and now nobody is replying..... Don't get paranoid, lad! I've just got nothing interesting or informative to say on the subject. Do you ever? Quote Link to comment Share on other sites More sharing options...
lomoto Posted September 7, 2006 Share Posted September 7, 2006 Bridgestones are STILL cr@p intresting about all the crunched Zeds turning up at auction /scrapyards etc. I wonder what proprtion are running Bridgestones Quote Link to comment Share on other sites More sharing options...
mugwump Posted September 7, 2006 Share Posted September 7, 2006 I'm worrying about my insurance renewal for next year! insurer: What car is it? mugwump: A 350z? insurer: Oooooh! Thats going to cost you *alot* ! Ha Ha Ha! (wrings hands together with glee) Quote Link to comment Share on other sites More sharing options...
kennyc Posted September 7, 2006 Author Share Posted September 7, 2006 I'm not upset I just went to bed I know you're not having a go and I will be taking extra care in the wet. I've only had the car since May and since then we haven't really had much rain dahn sarf. I just won't be replacing with Bridgestones when the time comes that's all. Quote Link to comment Share on other sites More sharing options...
Digsy Posted September 7, 2006 Share Posted September 7, 2006 Oh dear, clearly I hve upset everyone now, at least 15 people have read this thread since I posted and now nobody is replying..... Don't get paranoid, lad! I've just got nothing interesting or informative to say on the subject. Do you ever? Who rattled your cage? Quote Link to comment Share on other sites More sharing options...
Removed Posted September 8, 2006 Share Posted September 8, 2006 back on topic.... I learnt that I was right: wider tyres makes for more grip, fact. I had a first gut feeling that F1 cars could not be that wrong to choose as wide a tyre as possible and here's the reason, translated into english from Italian, courtesy of an Italian member of the 350Z club, race engineer I'll surely use wrong terminology in English, but hope you will still understand the goings on... "there are 2 reasons why wider tyres produce more grip, due to the laws of physics : 1) from a physics point of view if you consider non-deformable objects, the resistance generated (= energy trasmitted by the tyre) is proportional only to the energy that lies on top of it, multiplied by the grip coefficient. So if I increase the width area that touches the ground, the energy doesn't change. I simply have more surface, on which there is less specific energy (kg/ sq. cm) and I have no improvements to the " tangent strenght" (no idea on that term I'm afraid) transmitted. This is only valid for non deformable objects, though A tyre is NOT a non-deformable object and the wider is the contact area to the ground the less is the specific pressure for every sq. cm of tyre, and less is the deformation of the tyre. Deformation causes a loss of grip (adherence) 2) from a statistical point of view, not all tarmac has the same grip coefficient. With a wider tyre, you increase the chance of finding points on the tarmac that have a higher grip coefficient, and you reduce the risk of temporarily lose traction because say 30% of the tyre is touching a different type of tarmac. Consider that, once traction is lost, you go from a static friction coefficient (can't find the translation of this "moto di puro rotolamento" ) to a dynamic coefficient (again "moto di strisciamento") and the latter is always smaller than the former. In other words, if you break traction, you will have to take the foot off the gas to get back to the "puro rotolamento". Hence another reason why it's better to have wider tyres. So, unless there is excessive air pressure in the tyres which penalises traction, wider tyres give more grip." phew, that was hard Quote Link to comment Share on other sites More sharing options...
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