As I understand it, the benefit of low profile tyres is an enlarged footprint on the road surface, affording better grip.
Set against that is the increased chance of wheel damage on our increasingly potholed roads, tramlining tendencies, a harder ride, and of course the extra cost.
Does the pro outweigh the cons, or have I missed something?
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This is an interesting subject. The footprint really depends on the tyre size, and the benefit of low profile is more precise handling through less distortion of the side walls. My own problem with Proton GTi was repeatedly meeting, on a narrow road with kerbs, buses who seemingly would just as soon go over as past one, and having the near side rims duly graunched. Magentis does not have that problem, and having had it out today on a battery charging and running in expedition on the back roads I can say that the handling is not at all bad (double wishbones on the front). I think for day to day use low profile - less than\60 say - has little real advantage. One can get a good deal of the effect of low profile by blowing the tyres up (no Irish jokes!).
Why, while sports racers have very little sidewall at all, do Formula One cars have a reasonable amount; because that is the springing?
Tomo
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As I understand it the main advantage in roadholding terms is the reduced flexing of the tyre walls.
It is always a trade off between comfort and roadholding. Thats why the latest up-market saloons have electronically variable suspension settings to give the best of both worlds.
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Doesn't matter what the profile is, a 195 wide tyre puts down a 195 wide footprint. The benefit of lower profile is a stiffer sidewall, so less give in the corners, helping the tyre maintain a flat footprint despite the side loading. As the profiles get lower, manufacturers normally beef up the sidewalls even more to prevent too much distortion under impact load. It does make the ride stiffer, but the tyres are only one element of the whole suspension set up.
Most lowpro, large diameter tyres have an extended bead around the tyre to help protect the rim from damage. My R800VS has 215/45ZR17 tyres and has done 120k - never suffered any damage. These are the lowest pro tyres i've ever had on a road car and they help endow the car with tremendous cornering ability (helped by stiff suspension and a Torsen diff) but the ride is remarkably compliant and only gets jiggly on the worst surfaces.
Tramlining can be a problem, but again is dependant on more than just the profile. i found my car tramlined a lot less when I put much better tyres on it (Goodyear F1s in lieu of Uniroyal 440s).
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To my mind the low profile tyres are useful when you want to fit nice looking alloy wheels. Say 17" wheels on my Fiesta, then I would need some low profile tyres. They may not have many practical advantages, but they would look pretty nice. :)
Blue
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I'm not sure about more area being in contact with the road necessarily being an advantage, especially in the wet.
Grip is partly dependent on pressure;
Pressure is equal to Force/Area.
The force is exerted by the vehicle's weight, plus any dynamic forces that may have a vertical component, whilst driving.
Problem is, if you excessively increase the area, you reduce the pressure, which is fine if you're on nice dry well kept roads, but as soon as you hit a patch of water etc, then a significant area of the tyre is subjected to very little friction, the area that has good friction with the road will not have enough pressure to stop the car from sliding sideways.
Result - aqua planing, as I found out when my Mini derived Kit car with extra wide tyres ran into a wet patch. Any orninarily shod mini would have had no problem.
H
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Agreed with aquaplaning problem but reduced grip outside of the puddle scenario? I don't think so. Grip would remain the same overall, only grip per square inch (for example) would be reduced as the same level of overall grip is spread out over a larger area.
regards,
dan
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Mmm. Increased cornering speed. Very useful around the housing estate then. How much increase is there and is it really necessary?
Pandering to the shallow posers methinks.
Blue washer jets anyone?
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