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how does low profile tires afect handling
(91 posts, started )
Yes, the sidewalls contribution to cornering stiffness will be reduced, although the contact patches contribution should remain unaffected (and I think this the more prominent of the two). It would be nice to see data where only profile changed, and not width or radius.
judging by the kind of sidewall flex you can see on still pics and super slow mos of any car from a polo to an f1 under hard cornering i think the sidewall stiffness has a major impact on cornering stiffness
Quote from brt900 :hi,
i know low profile tyres make your cars handling pretty crap but could someone explain why it does

depends how you drive and on what roads, if your on the motorway all day their a dream... but if your in the city center ( as the last few have said ) they make life a nightmare.
Quote from theirishnoob :depends how you drive and on what roads, if your on the motorway all day their a dream... but if your in the city center ( as the last few have said ) they make life a nightmare.

If a crashy ride is what you prefer, then I suppose they might be a dream.
Quote from tristancliffe :If a crashy ride is what you prefer, then I suppose they might be a dream.

Are you suggesting that all cars with low profile tyres have a crashy ride?
Yes if they are an owner 'upgrade'. Yes on BMWs. Not necessarily (but quite often) in other cases.
Quote from tristancliffe :Yes if they are an owner 'upgrade'. Yes on BMWs. Not necessarily (but quite often) in other cases.

Ah yes, you are vehemently against any kind of modification to a factory car for some reason. I forgot about that
Quote from durbster :Ah yes, you are vehemently against any kind of modification to a factory car for some reason. I forgot about that

My father has worked in the automotive business for about 40 years (retired a few years ago). He's come a long way in the business and has tons of experience and knowledge. He wasn't just a mechanic or something. He studied machine engineering at the ETH (well known swiss university) and has worked and developed for several big companies. I'm not going to list details, but trust me when i say that he's very well educated when it comes to cars (and their development).

Something he always told me was that modifying cars is one of the most stupid things to do, because it'll empty your wallet, and ruin your car. Not talking about motorsport here... just average joe "tuning" crap.

I can see where Tristan is comming from. But i can also understand that most people don't believe it when they are told the truth... heck, i'm trying to tell a good friend of mine for months now that he'd be better of buying a stock car and keep it like that, instead of thinking about aftermarket wheels and suspension bits... but he won't listen of course.
Quote from durbster :Ah yes, you are vehemently against any kind of modification to a factory car for some reason. I forgot about that

Only the shit mods, or the ones that don't actually do anything, let alone what they are advertised as doing.
Quote from jibber :Something he always told me was that modifying cars is one of the most stupid things to do, because it'll empty your wallet, and ruin your car.

Well that depends on what's important to you. I suppose it's far easier to ruin your car than improve it I suppose, but even that is a matter of perspective. For example, I changed my suspension recently and it doesn't handle as well as it used to, but my wife thinks it's much better because it rides much better. To her it's a big improvement and to me it's not.

I've done a few mods to my car over the years and most of what I've done has improved the car.

The only one I can't justify from a performance aspect was putting a noisier exhaust on it but it's honestly one of my favourite purchases. It doesn't make it go any faster but it makes the driving experience massively more enjoyable, so was that a stupid thing to do?

I'm also about to put some bigger wheels on it. I'll let you know how that goes ...
Yes, the exhaust was a stupid thing to do. It doesn't make it a Ferrari.

As for bigger wheels... they'll probably be heavier too, which will affect the car quite a lot. I once had 17 inch wheels on an mx5, they looked real nice, but when i went back to the stock wheels i noticed how much better they really were (way better handling and agility, better acceleration, etc... and it wasn't just a slight difference, it was huge). If you can justify the worse performance for the looks, yeah, why not?

I am very tempted to get some nice wheels for my S2000, because honestly, i think some nice 17 inch wheels on that car look really nice... but then i would have to lower the car aswell, since otherwise it'd look stupid. And since i don't have 10k+ euro for a decent suspension setup, i'd have to go with a crappy one. The aftermath would be: Empty wallet, heavier wheels, ruined handling, nice looking car in a parking lot.

Quote from durbster :I've done a few mods to my car over the years and most of what I've done has improved the car.

Can you tell me which mods they were and how they improved the car?
#38 - Jakg
I can think of lots of mods i've done that have improved my car - all of which Tristan won't like

Stereo means I can actually listen to the music I want to listen to, and the new speakers mean I can listen to it without dieing a little inside - the new gearknob is more comfortable to use and also has the added bonus of not stabbing me in the hand every time I change gear, and the new lights mean I can see further at night which is helpful.

My new wheels give it a... different set of handling characteristics but I like the fact it A. Looks cool, B. Isn't illegal and C. Aren't likely to explode like my old rear tyres should of done...

All I will say is that there is no way these things weigh more than the ones I had before - while they may be 1" larger they aren't made out of steel and so are much MUCH lighter. And I have the added bonus of not having a totally ruined geometry because the car was designed for 14" and 15" wheels...
Quote from jibber :As for bigger wheels... they'll probably be heavier too, which will affect the car quite a lot...

You're right it would, which is why I wouldn't have chosen heavier wheels. The new ones are lighter.

Quote from jibber :Can you tell me which mods they were and how they improved the car?

- New seats with better support
- Chassis bracing for strength and to reduce cabin rattles
- Front splitter to reducefront end lift at higher speeds (surprisingly effective )
- Polybushes all round to improve all sorts of things (it's a 19 year old car so it's hardly surprising that one made a big difference).

I'm booked in for a full laser alignment after the new wheels arrive, which I should have done when I got the new suspension. Hopefully that will sort my issues with the new shocks and springs.

And early next year it'll be time for some more poke. Supercharger or turbo... not sure yet.
My stock wheels are 7kg without tyres. I'd have to spend quite a bit of cash to find 17's that aren't heavier.

Just out of curiosity, what car do you drive?

I can understand the seats (if the stock ones were REALLY bad regarding support), since weak support can be annoying.

I can understand the bushings, if the car's 19 years old, some parts will eventually need replacing... new stock bushings would have done the trick aswell tho, and would last another 15 years. Same goes for the suspension... the new aftermarket suspension might feel better now (after the alignment), but only because the previous one was 19 years old and worn out.

The splitter can help, but it's likely that it'll also mess up your aerodynamics. On a race track, it might actually help for a few split seconds faster lap times. Will you ever need it on the road? Probably not... will it make you look stupid on the road, probably yes.

What do you mean with chassis bracing? Strut brace (those will mainly help to total your car if you get into an accident)?

In the end it's all down to personal opinions. In my opinion, you maybe gain half a second around a track... you might aswell be slower in the end (see topgear episode where they had the challenge to make a normal car go as fast as an evo for 15 grand (including car)). I don't even want to know how much money you spent on the car already...
Quote from durbster :- New seats with better support
- Chassis bracing for strength and to reduce cabin rattles
- Front splitter to reducefront end lift at higher speeds (surprisingly effective )
- Polybushes all round to improve all sorts of things (it's a 19 year old car so it's hardly surprising that one made a big difference).

You see, I can't actually fault these. I'd question the seat if you changed it for appearance, but if you changed it for comfort/support then that's cool with me.
Quote from durbster :I'm booked in for a full laser alignment after the new wheels arrive, which I should have done when I got the new suspension. Hopefully that will sort my issues with the new shocks and springs.

Don't be fooled into thinking lasers are better. They just cost more.
About the suspension, it's a LOT easier to make a car softer and spoil the handling (which is, I think, what you dislike and what your wife approves of), than it is to make the car handle better. I can't imagine many people succeed, least of all when the springs they fit are shorter too.
Quote from durbster :And early next year it'll be time for some more poke. Supercharger or turbo... not sure yet.

If you want forced induction, go for a supercharger. They're far nicer to drive
Quote from Jakg :Stereo means I can actually listen to the music I want to listen to, and the new speakers mean I can listen to it without dieing a little inside

Either your old stereo didn't work, or you think that sound quality is even possible in a Proton. Waste of money. I doubt it sounds 'better' (though I might now sound different).
Quote from Jakg : - the new gearknob is more comfortable to use and also has the added bonus of not stabbing me in the hand every time I change gear

Ha ha ha ha. I'll accept your excuse, but you're probably just holding the gear lever wrong.
Quote from Jakg :and the new lights mean I can see further at night which is helpful.

Hmmmm. Maybe. I'll let you off this one
Quote from Jakg :My new wheels give it a... different set of handling characteristics but I like the fact it A. Looks cool, B. Isn't illegal and C. Aren't likely to explode like my old rear tyres should of done...

A - chav. B - yet. C - learn to drive or it'll happen again. Have you had the tracking checked, and the suspension examined? Have you learnt not to straddle speed humps? On the basis that B and C are silly reasons, you've done it for looks. Which is a chavvy thing to do. Chav
Quote from Jakg :All I will say is that there is no way these things weigh more than the ones I had before - while they may be 1" larger they aren't made out of steel and so are much MUCH lighter. And I have the added bonus of not having a totally ruined geometry because the car was designed for 14" and 15" wheels...

Did you weight them? Aluminium wheels tend to have to be thicker than pressed steel ones, and generally end up very close to the same weight - or even slightly heavier. The fact yours are an inch bigger makes that even worse. Not that the odd kilogram on a Proton would be noticeable!!

Quote from durbster :The only one I can't justify from a performance aspect was putting a noisier exhaust on it but it's honestly one of my favourite purchases. It doesn't make it go any faster but it makes the driving experience massively more enjoyable, so was that a stupid thing to do?

I de-catted my exhaust last year. Not for performance (it makes no measurable difference), but because it was going to fall to bits soon anyway, and I couldn't afford a replacement catalyst.

My first purchase was a de-cat pipe. Nothing fancy, just a tube with two flanges. My God it was loud. I felt like a right tosser (even more than normal) driving my car, and daren't use full throttle in case someone saw me. Two weeks later I was fed up with it, and bought a silencer de-cat pipe. The same thing, but with a silencer built in. Now it's no louder than before, but I don't have a failing cat. I don't see the point of loud cars. I even get fed up in the Exige, which is too loud to be enjoyable. Maybe at the F360/F430 sort of volume/scream it's acceptable, but any four cylinder should be banned from going over 25dB(a)
Quote from jibber :Just out of curiosity, what car do you drive?

Oh sorry, it's an MX-5. Pretty much everything I've done is due to old bits wearing out so I've chosen to upgrade rather than replace if possible.

As for the exhaust, you need to hear the difference before you can judge. There's no way I'd go back to a standard one now http://www.youtube.com/watch?v=hBfKim_g-4g

Quote from jibber :The splitter can help, but it's likely that it'll also mess up your aerodynamics.

Not true. You may already know that the front splitters were originally part of the NA MX-5 design so there's absolutely no doubt they improve the aerodynamics. Look at a standard nose, it sits about an inch higher than the sills - that's where the splitter should be.

They were removed for financial or transport reasons but either way, fitting one has made a significant difference. You may remember that above 60mph the front end goes quite light on the '5 and it loses a lot of its feel. The splitter sorts that out.

Quote from jibber :What do you mean with chassis bracing?

Two bars - one front and one rear to add a bit of chassis strength. They don't make much difference to the car on the road but they stop all the squeaks and creaks.

17" wheels on an MX-5? Now that is a bad modification

Quote from tristancliffe :My first purchase was a de-cat pipe. Nothing fancy, just a tube with two flanges. My God it was loud. I felt like a right tosser (even more than normal) driving my car, and daren't use full throttle in case someone saw me.

I must admit, when I first got this exhaust fitted it absolutely boomed. Driving down a built up street was like have a 20 piece brass band on board and it was pretty embarrassing. Thankfully, after a couple of weeks it quietened down and now it's just spot on. The volume's not important but the noise is. Stock MX-5 exhausts are pretty weedy.

Quote from tristancliffe :If you want forced induction, go for a supercharger. They're far nicer to drive

I am thinking that although I've driven some beautifully tuned turbos, and I know the right people to do the same. Although the path is more limited with the SC, I don't want monstrous power. I've driven a 350bhp MX-5 an it is absolutely insane.
Quote from durbster :
17" wheels on an MX-5? Now that is a bad modification

I was young and stupid and bought it like that (it was those heavy pro car wheels that mazda fitted to some of the NB models (the GT-R had them stock). But hey, for a 21 year old guy i was pretty smart already for going back to OEM wheels.

I thought you fitted some aftermarket spoiler lip, OEM splitter sounds more reasonable. Won't complain anymore...

As for the exhaust, i still think it sounds like a fart can...
Quiet is good. I see that now everytime i drive the S2000 and go into higher revs... it's not exactly a loud exhaust, but it's loud enough to hear it when i floor it... resulting in idiots (in their civics and bimmers) in my rearview mirror that want to race me whenever i go over 6k rpm... :bananadea

PS: Good car choice!
Yes, wise to lose the 17" wheels. Actually it's probably quite a good thing to buy them on the car because you might be able to sell them at a profit on replacements

Quote from jibber :As for the exhaust, i still think it sounds like a fart can...

Haha! If you're in the UK sometime I'll take you out in it

Quote from jibber :PS: Good car choice!



Although that's why I can't get rid of the bloody thing. Still makes me smile on every single journey after six years. Can't be bad
Quote from durbster :
- Front splitter to reducefront end lift at higher speeds (surprisingly effective )

Thats probably more effective in attracting 15y/o girls than it changes the aero. I have a wind tunnel measurment of a cars front end lift in normal shape and with a splitter type thing.

At 70mph the difference was 4.5 kilo. Sure you might have a super splitter that removes 9 kilo of lift, but thats neither noticable nor effective !
Some cars - mainly the Japanese ones - came with a splitter anyway. Adding them on the 5 can and does help (as long as you choose something vaguely resembling the Mazda part). Same with E-Types actually... The MX-5 is a lot more stable with one one too, presumably as it 'sorts out' turbulent ahead of the wheels or something. But I repeat; it has to be quite similar to the Mazda fitted one. A bit splitter or a bit apron won't help at all (probably).

I didn't leave my de-cat pipe on long enough to see if I'd get used to it or if it quietened. I think my current one has a deeper tone than standard, but there isn't much in it, and I only changed it to save money anyway

As for super/turbocharging, whilst it is possible to sort turbocharging nicely, you'll still end up with lag of some sort. And the MX-5 is such a wonderfully balanced car that can be steered using the wheel or the pedals. I'd guess (I've not tried either) that lag would ruin the handling of the car in this regard.

And don't fit a stupidly loud dump valve. Only knobs do that outside of rallying.
#47 - Jakg
Quote from tristancliffe :
Either your old stereo didn't work, or you think that sound quality is even possible in a Proton. Waste of money. I doubt it sounds 'better' (though I might now sound different).

So it's impossible for anything to sound better than a shitty cheap-o OEM HU / Speakers? My standard head unit was good but the speakers were beyond awful - the cones were made out of paper thinner than A4 ffs. My room isn't exactly perfect for audio reproduction but I can still hear the difference between different speakers - same in my car...

Ha ha ha ha. I'll accept your excuse, but you're probably just holding the gear lever wrong.

Erm, my gear stick wore through to a sharp bit of metal inside it, I fail to see how I could "hold it wrong" when any position of putting your hand around it lead to discomfort

Hmmmm. Maybe. I'll let you off this one
A - chav. B - yet. C - learn to drive or it'll happen again. Have you had the tracking checked, and the suspension examined? Have you learnt not to straddle speed humps? On the basis that B and C are silly reasons, you've done it for looks. Which is a chavvy thing to do. Chav
Did you weight them? Aluminium wheels tend to have to be thicker than pressed steel ones, and generally end up very close to the same weight - or even slightly heavier. The fact yours are an inch bigger makes that even worse. Not that the odd kilogram on a Proton would be noticeable!!

Did I weigh them? No. Did I carry them up and down my garden? Yes. I feel that the test of "how heavy do they feel" is enough to say these and the Toyota alloys weigh the same, whereas my steelies weigh 5 metric tons. Each. And also stop your rant about speedbumps, as I said there are NO speedbumps on my way to anywhere that it's even possible - they are all dead straight across the road. Feel free to insult my driving but don't hang yourself up on me hitting an obstacle i've never been anywhere near... And no, I don't care about the weight tbh - but every little helps

Just for Tristan again - out of the 360 miles a week I drive, I go over 4 speedbumps in Costessy Park & Ride which are all straight-accross-the-road jobs and totally even, and then over 3 normal ones with very very very sharp edges when I (rarely) drive into the UEA - I always attack them straight on for the very reason of avoiding grounding out (bad holiday experience <.<) and a sharp edge...

EDIT - And it's going into the garage on Tuesday...
Quote from tristancliffe :They (the manufacturers of aftermarket parts) are generally trying to pursuade idiots to buy their stuff, so they are made to a price, sold at a premium, and with next to no 'testing'.

Woah there fella, huge sweeping statements...

http://www.tein.com/
http://www.apexi-usa.com/
http://www.bilstein.de/home.html?int=1

Are just three aftermarket manufacturers who I can absolutely guarantee do a lot of testing and deliver a very premium product.

But I agree there are many who "modify" their cars buy simply buying these aftermarket items and not spending the time to correctly match component to car and then have it setup correctly. I think when building my car I spent 50% of the time making custom changes to the suspension to augment and improve the aftermarket parts fitted as well as using well experienced guys to setup the geometry.

e.g.
http://www.daftdonkey.com/gallery/main.php?g2_itemId=982
http://www.daftdonkey.com/gallery/main.php?g2_itemId=1150
@durbster:
Just out of interest, how big are you, and do you think a 1,97m guy could fit in that car? I somewhat fancy a small rwd car, and a cheap MX-5 is on sale nearby. I heard that the newer once are actually smaller inside than the old (sat in the newest one on the IAA, couldn't close the roof :razz
hi lots of discussion here cool pretty good readign it all im thinking of so me 16" wheels a bit bigger than the current wheels as the 15" now have quite a big sidewalll and found a decent set of 16" on ebay and i think they where 195/45 is that a ok size profile tire. i was also looking at some spax suspension kits that lower the car 40mm because the suspension on the corsa now is pretty old tbh

how does low profile tires afect handling
(91 posts, started )
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