Andrew, Yeah just crapping on as usual...:) My own opinion is; Just get out there and 'run what you brung'. It is almost always better to refine what you have than to start from scratch. I am happy to leave the excessive 'tool polishing' and 'bench racing' to the F1 people!
The unfortunate thing about motorsport is that it is generally so close and even. Everything is seconds, and tenths of seconds. You might dismiss some modifications as not making much difference, but these small improvements add up and can make enough of a difference. It would be interesting to jack up the car and put some mud, dirt or sand under the wheel and lower the car onto it. Compare the 205/60-13 and the 195/60-13 footprint. As for F1 <*yawn* does anyone still watch it?> they have no suspension movement because of the change in aerodynamic forces with the changing speeds. If they had working suspension the cars would bottom out at high speed and tend to rock backwards and forwards violently at other times. Racing tyres are stiff crossply construction which is different to the flexible radial tyres that we use on the road. I don't think that anyone can categorically say that a particular profile works best. Nick > From: "Andrew Greenbury" <[EMAIL PROTECTED]> > Subject: Re: What size wheels are best? > Date: 05/04/2002 12:51:24 > To: [EMAIL PROTECTED] > > Hey there Nick, > > Yeah some good and interesting points in there. What it comes > down to I think is the differences between 13s and 14s in terms of > these particular tyres (dimensional, constructional and > performance) are going to be pretty similar. eg for most of the > things we have been discussing we are talking dimensional > differences in the order of <10mm (unloaded radius, contact width > etc etc). Of course, if we were talking what is the optimum > wheel/tyre size combo without constraints then we'd really get > some discussion going :) > > As mentioned the greatest advantage of the larger diameter rims > would be room for brakes, but if Mark is already outbraking > opposition, then as Terry suggests brake hardware/performance > must be comparable. > > The F1 reference wasn't a comparison of a 1600 to an F1 machine > :) But to the fact that as the pinacle of technology they have > chosen to run such a high tyre profile for a reason. To run low > profile/vertically stiffer tyres with slightly softer springs would be > equivalent to todays practically rigid chassis with tyres as springs, > and easier/more controllable too. Apparently an analysis has been > done that finds the optimum tyre profile for performance is ~80 or > so (??!) but I cant find its source so who knows how that was > arrived at. > > Andrew > > > Mark, > > > > The following statements are unproven, untenable, and indefensible:) > > > > </crap on> > > > > You'd need very wide rims to stretch the sidewall of your 205/60-13's enough > > to get the best performance out of them. > > If you don't stretch them them flex in the sidewalls will give bad driver > > feedback and will heat up the tyres faster. > > Because the 14's are slightly narrower, but still have the same aspect ratio > > (60%) the sidewalls will be shorter. So you could use quite sensible rims > > and still stretch the sidewall. > > > > You also have a benefit of being able to use a softer compound since they > > are easier to set up better. ie the 14's won't heat up as quickly as the > > 13's > > > > The wide, but short, contact patch of the 205/60-13's would be more > > sensitive to camber change (bumps, dynamic or steady state cornering etc). > > The Semi-trailing arm rear-end and MacPherson strut front-end are not very > > precise suspension methods and suffer from lots of camber, castor, scrub and > > toe change > > > > The 195/60-14 tyres are narrower (obviously). This doesn't mean that there > > is less rubber on the road as the increased rolling diameter means the > > contact patch, whilst narrower, is also longer than for the 13's. This long > > and thin contact patch is less sensitive to camber changes. > > > > The other, and main, benefit of 14's is the increased room for brakes and > > brake cooling. > > If you are not getting brake fade you probably aren't going hard enough :) > > Seriously, it really depends on the car, track, budget and driver so I can't > > really say anything useful here. > > > > 14's will increase the ride height of your car, you would have to lower it > > again to get back the CofG and this would cause the suspension geometry > > front and rear to get worse.ie going to 14" requires suspension geometry > > changes. > > > > You can't really compare your car to an F1 car as F1 cars have effectively > > zero suspension movement and the tyres are the only actual deflecting > > element. > > > > All high performance and competition saloon cars go for the biggest wheel > > and lowest profile tyre that is allowable. This gives more room for brakes > > and reduces sidewall flexing (which generates heat) so that they can run a > > softer compund and the driver can get better quality feedback. > > </crap off> > > > > PS When the flag drops and the bullshit stops, how do you go when you race > > together? Is he faster down the straights, say, and you are better under > > brakes and quicker through certain turns ? etc... > > If he is particularly faster through a bumpy corner, or if your performance > > drops off, relative to his, as the race progresses, I'd suspect the tyres. > > > > Regards, > > Nick > > ----- Original Message ----- > > From: "Mark Alford" <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]> > > Sent: Thursday, April 04, 2002 5:16 PM > > Subject: Re: What size wheels are best? > > > > > > > Andrew, > > > > > > Needless to say, he runs 14" wheels and we are usually pretty close when > > it > > > comes down to lap times etc. Also, I think nearly everyone else runs 14" > > > wheels, but that doesn't mean they are all right! > > > > > > He has a number of points - some of them I find difficult to swallow, > > others > > > have some credence. > > > > > > 1) Run 14" wheels and let the torque (I run an FJ - which is very torquey) > > > pull the car out of the corner with the 14" wheels. - my argument is that > > I > > > could change diff ratios if that is what I wanted to achieve. > > > > > > 2) 14" rim will have a larger outer diameter, therefore more rubber - > > which > > > in turn means the tyres will not get as hot because you are using more > > > rubber to do the same task. (I think he's clutching at straws here!) > > > > > > 3) 195/60 will have a smaller side wall than a 205/60 - which is true. > > > But.....the 205 is only a 13" when the 195 is a 14" therefore won't they > > > pretty much cancel each other out or at least the contact patch of the 205 > > > must be worth something here? > > > > > > 4) The whole bigger brakes argument - my opinion there is that I am > > already > > > out braking other people so why would I need bigger brakes? I am running > > > four spots with a 260mm vented disk up front, with disks in the rear > > also - > > > stops pretty good! > > > > > > He had some others also, but they were a bit left of field and/or he > > didn't > > > have a good explanation as to why. I'm all for taking advise, hence I > > posted > > > this message, but I don't like to change things simply on someone's word - > > I > > > like to know why, and so far, no one has managed to show me why 14" wheels > > > will give me a better package than what I already have, or will bring my > > lap > > > times down any further. > > > > > > Cheers, > > > > > > Mark. > > > > > > ----- Original Message ----- > > > From: "Andrew Greenbury" <[EMAIL PROTECTED]> > > > To: <[EMAIL PROTECTED]> > > > Sent: Thursday, April 04, 2002 4:49 PM > > > Subject: Re: What size wheels are best? > > > > > > > > > > Hey Mark, > > > > > > > > No worries - what is the view of the guy you have been having a > > > > long running discussion with?? > > > > > > > > > > > > > Cheers Andrew, I appreciate the feedback. > > > > > > > > > > So far nothing has been said to make me think that 14's are the way to > > > go. > > > > > This justifies what I have been telling myself for ages, just needed > > > some > > > > > other opinions to confirm it. > > > > > > > > > > Thanks to all who have replied. > > > > > > > > > > Mark. > > > > > > > > > > P.S. If any one thinks that 14's would be the way to go, I would still > > > like > > > > > to hear why. > > > > > ----- Original Message ----- > > > > > From: "Andrew Greenbury" <[EMAIL PROTECTED]> > > > > > To: <[EMAIL PROTECTED]> > > > > > Sent: Thursday, April 04, 2002 4:20 PM > > > > > Subject: Re: What size wheels are best? > > > > > > > > > > > > > > > > Hi Mark, > > > > > > > > > > > > yeah I agree with Errol for the same kind of reasons esp in your > > > > > > racing context. Your rubber choice is greater, and you already have > > > > > > the 13s. > > > > > > > > > > > > Rotational inertia is proportional to mass*radius^2, so the > > > > > > distribution of mass around the wheel has a greater effect than the > > > > > > overall weight itself. The lower the inertia the less torque/force > > > > > > required to accelerate (and brake) the wheel. Also the wheel will > > > > > > accelerate/brake faster. > > > > > > > > > > > > Because of this as Errol said, bigger rims also require bigger > > > > > > brakes, but bigger brakes add more rotating mass etc etc. > > > > > > Generally, larger diameter tyres weight more too, and this mass > > > > > > has the largest radius. > > > > > > > > > > > > >From a handling point of view, the 13s give you a wider contact > > > > > > patch and a larger grip envelope. Because you have to keep the 60 > > > > > > profile, the difference in sidewall thickness should be similar as > > > > > > Ben mentioned, so you would expect the cornering stiffness of both > > > > > > sizes to be similar. The perception of the lower the profile the > > > better > > > > > > the performance isnt always the case - what size tyres do F1 use? > > > > > > > > > > > > Andrew > > > > > > > > > > > > > Ok Errol, > > > > > > > > > > > > > > I currently have the 13" wheels. Brake wise I am running a set of > > > > > > > four piston sumitomo callipers. These callipers are apparently > > > > > > > works Nissan Callipers from an older model Japanese 300ZX. The > > > > > > > Callipers are not alloy, and are quite weighty. The disc is of > > > > > > > unknown origin (came with the car) but is 260mm diameter and is > > > > > > > vented. > > > > > > > > > > > > > > This setup works very well in it's current configuration. If > > > > > > > however, I was to go to 14" wheels, what size rotor and which > > > > > > > Callipers would you recommend? > > > > > > > > > > > > > > Also, from a handling point of view, would the 14" wheels provide > > > > > > > better handling? Keeping in mind I still have to run the 60 series > > > > > > > tyre, and would be forced to run a 195 as opposed to the 205/60/13 > > > > > > > I am currently running? > > > > > > > > > > > > > > What do you think? > > > > > > > > > > > > > > Mark. > > > > > > > ----- Original Message ----- > > > > > > > From: E Smith > > > > > > > To: [EMAIL PROTECTED] > > > > > > > Sent: Thursday, April 04, 2002 11:43 AM > > > > > > > Subject: RE: What size wheels are best? > > > > > > > > > > > > > > > > > > > > > Its also a matter of moments and braking toque. Assuming the > > > > > > > same caliper and applied pedal force in every condition: - > > > > > > > > > > > > > > The larger the rotational diameter of the wheel/tyre, the disc > > > > > > > required must be proportionally larger diameter to maintain the > > > > > > > same braking effort. > > > > > > > > > > > > > > > > > > > > > > > > > > > > The classic wheel size example is the "EVO mock up" lancer with > > > > > > > the 9" discs inside 18" wheels and they wonder why they will not > > > > > > > stop. I have a feeling that a lot of accidents recently have been > > > > > > > caused by these mismatches of tyre - wheel / brake - caliper > > > > > > > combinations. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I personally like 13 X 7" rims as the range of rubber is better > > > > > > > for this size wheel, from treaded competition tyres to slicks. > > > > > > > They are also usually lighter. The next size up is 15" rims to > > > > > > > get a good selection of rubber. As the diameter goes up though so > > > > > > > does the price. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Cheers > > > > > > > > > > > > > > Feral Errol > > > > > > > > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > From: [EMAIL PROTECTED] > > > > > [mailto:[EMAIL PROTECTED]]On Behalf Of Mark Alford > > > > > > > Sent: Thursday, 4 April 2002 9:26 AM > > > > > > > To: Ozdat discussion list > > > > > > > Subject: What size wheels are best? > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hey listers, > > > > > > > > > > > > > > > > > > > > > > > > > > > > I have been having a long running discussion with a guy I race > > > with > > > > > regarding wheel sizes, and what size wheel is best to run. I thought I > > > might > > > > > throw the question open to the list and see what thoughts are out > > there. > > > > > > > > > > > > > > > > > > > > > > > > > > > > What I would like to know is - What size (diameter) wheel is > > > > > > > best to run? the choice is between two sizes 13" and 14" (both > > > > > > > with 7" width). Something else that also needs consideration is > > > > > > > the tyre that I must run. If I run the 13" I can use a 205/60. If > > > > > > > I run the 14" I must run a 195/60. (Everyone must use a 60 series > > > > > > > tyre) > > > > > > > > > > > > > > > > > > > > > > > > > > > > So who out there has some thoughts on which combination I should > > > run? > > > > > I would also like to know the reasons behind peoples thoughts. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I look forward to the feedback. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Mark. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > --membersozdat------------------------------------------------------- > > > > > > > OZDAT Mailing List Please Note:- > > > > > > > Send (un)subscribe requests to [EMAIL PROTECTED] > > > > > > > Send submissions to [EMAIL PROTECTED] > > > > > > > No unauthorised redistribution of this email > > > > > > > http://www.ozdat.com/ozdatonline/index.htm > > > > > > > http://www.ozdat.com/ozdatonline/listindex.html > > > > > > > http://www.mail-archive.com/[email protected]/ > > > > > > > > > --------------------------------------------------------------------- > > > > > > > > > --membersozdat------------------------------------------------------- > > > > > > > OZDAT Mailing List Please Note:- > > > > > > > Send (un)subscribe requests to [EMAIL PROTECTED] > > > > > > > Send submissions to [EMAIL PROTECTED] > > > > > > > No unauthorised redistribution of this email > > > > > > > http://www.ozdat.com/ozdatonline/index.htm > > > > > > > http://www.ozdat.com/ozdatonline/listindex.html > > > > > > > http://www.mail-archive.com/[email protected]/ > > > > > > > > > --------------------------------------------------------------------- > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > This message was sent through MyMail http://www.mymail.com.au --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[email protected]/ ---------------------------------------------------------------------
