Handling - low or high profile tyres??
Discussion
TA14 said:
mikey k said:
kambites said:
Assuming I'm allowed to set the damping up to suit, I'd (within reason) go for whatever ends up with the lowest unsprung mass.
bingoI've often found by going down a wheel size you can go wider and lighter.
Given you the benefit of more grip for less weight
I remember Performance VW doing a handling test with a MKII golf a good few years ago, using 14", 15", 16" and 17" wheels for comparison - the quickest time around a tight/twisty circuit was on 15" wheels with a 195/50 tyre (compared to the standard 185/55 spec'd at the time by VW). So as above, I think there definitely a sweet spot
Article from Car & Driver magazine, testing different sized wheels & tyres on the same 2010 VW Golf.
As you'd expect, the largest wheel / lowest profile tyre option isn't necessarily the sweetspot, particularly if acceleration and/or fuel economy are important factors for consideration:
http://www.caranddriver.com/features/effects-of-up...
As you'd expect, the largest wheel / lowest profile tyre option isn't necessarily the sweetspot, particularly if acceleration and/or fuel economy are important factors for consideration:
http://www.caranddriver.com/features/effects-of-up...
Miglia 888 said:
Article from Car & Driver magazine, testing different sized wheels & tyres on the same 2010 VW Golf.
As you'd expect, the largest wheel / lowest profile tyre option isn't necessarily the sweetspot, particularly if acceleration and/or fuel economy are important factors for consideration:
http://www.caranddriver.com/features/effects-of-up...
Interesting article, thanks. As you'd expect, the largest wheel / lowest profile tyre option isn't necessarily the sweetspot, particularly if acceleration and/or fuel economy are important factors for consideration:
http://www.caranddriver.com/features/effects-of-up...
When I said there is a sweet spot earlier, what I meant was, you need a balance between traction and bite, go too low on the profile and you loose bite going into the corners, go too high and you loose too much traction as soon as the surface is anything other than really smooth.
My M3 was far better on 18's as the back end dug in and ultimately gave more grip than the 19s, which although performed better on a handful of surfaces, in 90% of situations started to skip about at the back.
Both the 18s and 19s were shod with XL rated Michelin Pilots, but the 18s definitely performed better for handling, as well as being more comfy too.
My M3 was far better on 18's as the back end dug in and ultimately gave more grip than the 19s, which although performed better on a handful of surfaces, in 90% of situations started to skip about at the back.
Both the 18s and 19s were shod with XL rated Michelin Pilots, but the 18s definitely performed better for handling, as well as being more comfy too.
gizlaroc said:
When I said there is a sweet spot earlier, what I meant was, you need a balance between traction and bite, go too low on the profile and you loose bite going into the corners, go too high and you loose too much traction as soon as the surface is anything other than really smooth.
Did you mean the opposite? i.e. high profile/more flex/less 'bite'?gizlaroc said:
My M3 was far better on 18's as the back end dug in and ultimately gave more grip than the 19s, which although performed better on a handful of surfaces, in 90% of situations started to skip about at the back.
Both the 18s and 19s were shod with XL rated Michelin Pilots, but the 18s definitely performed better for handling, as well as being more comfy too.
Very interesting. On 18's my E46 rides better over crap surfaces but handling wise lost the precision of the 35/30 profiles. The back end hasn't broken loose without me driving in a way where I expect it to, and I have all ball joints from the CSL rather than the std mix of rubber bushes & ball joints. Both the 18s and 19s were shod with XL rated Michelin Pilots, but the 18s definitely performed better for handling, as well as being more comfy too.
It is quite possible your RTABS were worn, which is a common problem.
no one has mentioned that bigger wheel rim = larger brake disks = improved stopping, something that needs to be considered in the modern world of 400BHP 2 ton AMG / M5 / RS6 etc cars.
however, as mentioned already its the unsprung weight balance that surely has to be it for "normal" cars
I ran 17" wheels and 45 section tires on my '75 911, the larger wheels there to accommodate the porsche boxter brakes that we fitted (minus the ABS)
however, as mentioned already its the unsprung weight balance that surely has to be it for "normal" cars
I ran 17" wheels and 45 section tires on my '75 911, the larger wheels there to accommodate the porsche boxter brakes that we fitted (minus the ABS)
The biggest factor that will determine the sweet spot is how accurately the camber changes reflect the body movement of the vehicle.
If they do not accurately track the roll angles then a higher profile tyre will give a far better level of grip and progression as tyre sidewall flex will allow some amount of correction and allow the tread to track better on the road surface.
Another factor to bear in mind is unsprung weight. A larger alloy with a low profile tyre will almost always weigh more than a smaller rim with a high profile tyre.
The greater unsprung mass impacts the ability of the suspension to follow the road surface, especially when coupled with the relative lack of tyre sidewall compliance of a higher profile tyre.
The large rim/low profile tyre thing seems to be a predominantly UK based phenomenon on road cars and in my view is often an example of style overriding function.
My personal preference is smaller rim and higher profile tyre (45 or 50 profile seems a good compromise depending on the vehicle).
If they do not accurately track the roll angles then a higher profile tyre will give a far better level of grip and progression as tyre sidewall flex will allow some amount of correction and allow the tread to track better on the road surface.
Another factor to bear in mind is unsprung weight. A larger alloy with a low profile tyre will almost always weigh more than a smaller rim with a high profile tyre.
The greater unsprung mass impacts the ability of the suspension to follow the road surface, especially when coupled with the relative lack of tyre sidewall compliance of a higher profile tyre.
The large rim/low profile tyre thing seems to be a predominantly UK based phenomenon on road cars and in my view is often an example of style overriding function.
My personal preference is smaller rim and higher profile tyre (45 or 50 profile seems a good compromise depending on the vehicle).
Hoofy said:
It's something I've wondered about:
Tyres aren't rubberband thick like on a chavved up BMW. A good 2-3" of rubber - thicker than the tyres on my standard 17" wheels.
You can't compare motorsport tyres with road tyres. The deflection on slicks with higher profiles is still less than a low profile road sport tyre.Tyres aren't rubberband thick like on a chavved up BMW. A good 2-3" of rubber - thicker than the tyres on my standard 17" wheels.
mwstewart said:
Hoofy said:
It's something I've wondered about:
Tyres aren't rubberband thick like on a chavved up BMW. A good 2-3" of rubber - thicker than the tyres on my standard 17" wheels.
You can't compare motorsport tyres with road tyres. The deflection on slicks with higher profiles is still less than a low profile road sport tyre.Tyres aren't rubberband thick like on a chavved up BMW. A good 2-3" of rubber - thicker than the tyres on my standard 17" wheels.
Plus, wheel size is dictated by regulations.
'Handling' is an immensely subjective thing. Some people simply define a bone shattering ride as good handling (sporty innit), others define it as essentially 'will it drift', others define it as just absolute grip. Personally I think handling is a catch all term that encompasses a huge array of variables, only some of which are affected by the profile of your tyres. That said I would always go for the smallest, lightest wheel with the tallest sidewalls available on a road car, in my experience this gives the best results on uneven surfaces (i.e. most roads). For a lap of a perfectly smooth racetrack however I would more likely go for bigger rims and skinnier, stiffer tyres.
People who drive or have experience of cars such as MX5's or Caterhams, are more likely to grasp the inherent difference between the concepts of handling and grip.
My old MX5, for example, handled really nicely but didn't have much in the way of outright grip. In contrast, my old man's new Volvo S60 has a LOT of grip, but doesn't handle well at all. Any loading and the car just feels...yuk.
Drives me nuts when I see people chucking on cheap "coilovers" then thinking they've transformed the handing of their car for the better!
Also, for those pointing out GT & F1 cars, don't forget the metric f*cktonne of aero those cars have too.
Then you've got traction, but that's another discussion
My old MX5, for example, handled really nicely but didn't have much in the way of outright grip. In contrast, my old man's new Volvo S60 has a LOT of grip, but doesn't handle well at all. Any loading and the car just feels...yuk.
Drives me nuts when I see people chucking on cheap "coilovers" then thinking they've transformed the handing of their car for the better!
Also, for those pointing out GT & F1 cars, don't forget the metric f*cktonne of aero those cars have too.
Then you've got traction, but that's another discussion
There is no simple answer. This is what I think…
Higher profile tyres are generally slower through transient manouvres, as they generally have a lower yaw eigenfrequency and less yaw damping.
Higher profile tyres give more warning to the driver that ultimate grip is approaching, but the actual breakaway of grip doesn’t seem any less benign than low profile tyres, especially in transient manouvres, where it is usually much worse.
Regards vertical behavior, I think the importance of unsprung mass is a little overstated. It is much better to have a wheel and tyre assembly that is properly damped, by offering a fairly direct connection between the road and the damper, than a wheel and tyre assembly that is a kilo or two lighter. The tyre should be stiff enough vertically to actually deflect the wheel over bumps, to activate the damper. Using a tyre as a damper is pretty rubbish.
Some people drive very smoothly, with smooth turn in and considered steering. Higher profiles work well for this steering type.
Some people are very aggressive in direction changes, with sharp steering inputs. Lower profile works better here.
Higher profile tyres are generally slower through transient manouvres, as they generally have a lower yaw eigenfrequency and less yaw damping.
Higher profile tyres give more warning to the driver that ultimate grip is approaching, but the actual breakaway of grip doesn’t seem any less benign than low profile tyres, especially in transient manouvres, where it is usually much worse.
Regards vertical behavior, I think the importance of unsprung mass is a little overstated. It is much better to have a wheel and tyre assembly that is properly damped, by offering a fairly direct connection between the road and the damper, than a wheel and tyre assembly that is a kilo or two lighter. The tyre should be stiff enough vertically to actually deflect the wheel over bumps, to activate the damper. Using a tyre as a damper is pretty rubbish.
Some people drive very smoothly, with smooth turn in and considered steering. Higher profiles work well for this steering type.
Some people are very aggressive in direction changes, with sharp steering inputs. Lower profile works better here.
Gassing Station | Suspension, Brakes & Tyres | Top of Page | What's New | My Stuff