Why do we have to have low profile tyres to look "sporty"?
Discussion
legless said:
Interestingly, when I worked for one OEM, we ran a competitor evaluation fleet.
A few times, we had examples of the 'comfort' and 'sport' trims of cars simultaneously that were otherwise identical. Think a 530d SE and a 530d M-Sport, and a A4 SE and a A4 S-line.
Without exception, we could consistently set faster times on pretty much any test circuit with the 'comfort' trim. The spring and rebound rates on the suspension were so much better judged, and the higher profile tyres were better at absorbing imperfections in the surface, the net effect being that the tyre was in contact with the road surface more of the time.
That sounds rather odd. I've always found the sportier chassis specifications to be faster on track. A few times, we had examples of the 'comfort' and 'sport' trims of cars simultaneously that were otherwise identical. Think a 530d SE and a 530d M-Sport, and a A4 SE and a A4 S-line.
Without exception, we could consistently set faster times on pretty much any test circuit with the 'comfort' trim. The spring and rebound rates on the suspension were so much better judged, and the higher profile tyres were better at absorbing imperfections in the surface, the net effect being that the tyre was in contact with the road surface more of the time.
Kawasicki said:
That is weird, as usually a sports tyre has more grip than a comfort tyre. The chassis tunes on the sports versions must have been dangerous to drive on a typical bumpy country road, under damped to the extent that they were unable to absorb imperfections.
I must say I’m sceptical.
I'm not saying that the sports chassis was bad or dangerous. Merely that the comfort chassis was better, and we could consistently set better laptimes using it. The sports chassis could still absorb most imperfections, but the comfort chassis was better at it. I must say I’m sceptical.
I take your point about the tyres, but in general OEMs tend to use the same type of tyre regardless of the chassis tune, except for 'proper' fast variants. Audi will fit a Conti SportContact for example both on an A4 SE and an A4 S-line. It's just whoever gives them the best deal at the time.
I think the car manufacturers were quite happy to pander to customer desires of 'fashion' when it comes to skinny tyres on large rims. Firstly they can sell more options and secondly, when the car gets used on British roads, they can sell replacement wheels because the originals were smashed to bits in potholes.
I am not a fan personally and replaced the (215 35) 17 inch alloys on my Alfa with (205 60) 15 inch alloys and the ride is no longer back breaking. I breathed a sigh of relief during my first trip out on the new wheels...
As for the perceived performance advantages of low profiles, I don't buy it. There is supposed to be sidewall flex under load that puts the full tread face onto the road (taking into account camber) and with super low profiles there pretty much isn't any flex. Plus the tyre itself absorbs bumps and does it very quickly, probably quicker than the suspension, which means the rubber is in contact with the tarmac more of the time, therefor more grip in the corners therefor faster times.
There is a balance of course...
I am not a fan personally and replaced the (215 35) 17 inch alloys on my Alfa with (205 60) 15 inch alloys and the ride is no longer back breaking. I breathed a sigh of relief during my first trip out on the new wheels...
As for the perceived performance advantages of low profiles, I don't buy it. There is supposed to be sidewall flex under load that puts the full tread face onto the road (taking into account camber) and with super low profiles there pretty much isn't any flex. Plus the tyre itself absorbs bumps and does it very quickly, probably quicker than the suspension, which means the rubber is in contact with the tarmac more of the time, therefor more grip in the corners therefor faster times.
There is a balance of course...
My Swift Sport still has its winters fitted 15” 70 profile come April it’ll be back on the 17” 40 profile summers, the difference in the noise and ride between the two sets is considerable not favouring the summers.
I’ve been thinking for a while since seeing the “rent4ring” Swifts on the smaller wheels with the tall profile tyres it may be good to swap to a set-up like that for our very poorly maintained roads.
I’ve been thinking for a while since seeing the “rent4ring” Swifts on the smaller wheels with the tall profile tyres it may be good to swap to a set-up like that for our very poorly maintained roads.
k low profiles. I’ve just bought a new, automatic supermini for my partner, with a 1 litre (albeit turbocharged) engine generating a heady 115PS. It’s fitted with 18” wheels (which, to be fair were optional...) and shod with 215/45/18 tyres 
The ride’s not actually that bad, but the rear discs are completely lost...
The ride’s not actually that bad, but the rear discs are completely lost...
Im part of the minority, i actually chose my specific car out of all the other examples mainly because it had 16 inch rims instead of the 17 or 18s that every other trim level came with. The tyre size is 205/55/16 all 4 corners, i was going to get 215 on the back but figured as bmw didnt stagger it i probably shouldnt either.
There has never been a single second where i regretted my decision, in terms of looks i feel the spoke design is more important than how large the rim is and with my car and rim i have the spoke design is imo the best of the bunch by a long way.
With regards to performance i feel for my car
smaller rims provide greater performance than the 18 inch would, as being a 185hp (remapped) derv the acceleration supposedly benefits tremendously from having smaller/lighter rims (0.5 second off 0-60 at an estimate based on guesswork from seeing a similar test carried out on diff car)
The handling has never felt compromised at all or felt like it was the limiting factor at any point no matter how nutty ive taken a corner so the perceived benefit of larger rims likely wouldnt provide any noticeable improvement.
The biggest benefit i see to smaller rims though is the confidence it inspires on the uks roads, i can fly around b roads safe in the knowledge that even if there is a crater on the exit of the bend i can crash through it and come through unscathed,the ride quality is sublime and limo-like compared to every other car ive taken a ride in in the last 5 years and as an aside because it has skinnier tyres too it also means i can drive with more confidence in rain or snow.
Add in to that that the tyres are more likely to protect from damage from bumps or kerbs and the much lower replacement cost vs lower profiles and you have a logical conclusion. (at least in this case) Smaller = better
There has never been a single second where i regretted my decision, in terms of looks i feel the spoke design is more important than how large the rim is and with my car and rim i have the spoke design is imo the best of the bunch by a long way.
With regards to performance i feel for my car
smaller rims provide greater performance than the 18 inch would, as being a 185hp (remapped) derv the acceleration supposedly benefits tremendously from having smaller/lighter rims (0.5 second off 0-60 at an estimate based on guesswork from seeing a similar test carried out on diff car)
The handling has never felt compromised at all or felt like it was the limiting factor at any point no matter how nutty ive taken a corner so the perceived benefit of larger rims likely wouldnt provide any noticeable improvement.
The biggest benefit i see to smaller rims though is the confidence it inspires on the uks roads, i can fly around b roads safe in the knowledge that even if there is a crater on the exit of the bend i can crash through it and come through unscathed,the ride quality is sublime and limo-like compared to every other car ive taken a ride in in the last 5 years and as an aside because it has skinnier tyres too it also means i can drive with more confidence in rain or snow.
Add in to that that the tyres are more likely to protect from damage from bumps or kerbs and the much lower replacement cost vs lower profiles and you have a logical conclusion. (at least in this case) Smaller = better
Debaser said:
legless said:
Interestingly, when I worked for one OEM, we ran a competitor evaluation fleet.
A few times, we had examples of the 'comfort' and 'sport' trims of cars simultaneously that were otherwise identical. Think a 530d SE and a 530d M-Sport, and a A4 SE and a A4 S-line.
Without exception, we could consistently set faster times on pretty much any test circuit with the 'comfort' trim. The spring and rebound rates on the suspension were so much better judged, and the higher profile tyres were better at absorbing imperfections in the surface, the net effect being that the tyre was in contact with the road surface more of the time.
That sounds rather odd. I've always found the sportier chassis specifications to be faster on track. A few times, we had examples of the 'comfort' and 'sport' trims of cars simultaneously that were otherwise identical. Think a 530d SE and a 530d M-Sport, and a A4 SE and a A4 S-line.
Without exception, we could consistently set faster times on pretty much any test circuit with the 'comfort' trim. The spring and rebound rates on the suspension were so much better judged, and the higher profile tyres were better at absorbing imperfections in the surface, the net effect being that the tyre was in contact with the road surface more of the time.
On a test track or a normal road, hello wheel skitter
Flibble said:
Nanook said:
That's a rear wheel.
I take your point, but if you look at the front brakes on that car, there's not nearly as much clearance as that picture shows.
And I'm assume you're not proposing fitting smaller diameter wheels to the back of the car, than are on the front?
Interesting point though. Some cars have larger diameter wheels on the back, has anyone ever built a car with larger diameter wheels on the front before?
Front to rear brake difference is usually about an inch of diameter, give or take? Still going to be acres of space on that fitment.I take your point, but if you look at the front brakes on that car, there's not nearly as much clearance as that picture shows.
And I'm assume you're not proposing fitting smaller diameter wheels to the back of the car, than are on the front?
Interesting point though. Some cars have larger diameter wheels on the back, has anyone ever built a car with larger diameter wheels on the front before?
I've heard of some slightly larger front wheels (Audi with the RS3), but only width, not diameter.
Bennet said:
Who cares what the fashion trend is? You can buy any size of wheel and tyre you want, aftermarket. So go for it.
It can get messy with insurance though, especially with the main stream companies. LV= had a little paddy when we I winter wheel and tyre set on wife's Tiguan, as they're 16" wheels, rather than the standard 17". They only seemed to accept it as I said it was VW's official winter set for Tiguan.ChemicalChaos said:
Debaser said:
legless said:
Interestingly, when I worked for one OEM, we ran a competitor evaluation fleet.
A few times, we had examples of the 'comfort' and 'sport' trims of cars simultaneously that were otherwise identical. Think a 530d SE and a 530d M-Sport, and a A4 SE and a A4 S-line.
Without exception, we could consistently set faster times on pretty much any test circuit with the 'comfort' trim. The spring and rebound rates on the suspension were so much better judged, and the higher profile tyres were better at absorbing imperfections in the surface, the net effect being that the tyre was in contact with the road surface more of the time.
That sounds rather odd. I've always found the sportier chassis specifications to be faster on track. A few times, we had examples of the 'comfort' and 'sport' trims of cars simultaneously that were otherwise identical. Think a 530d SE and a 530d M-Sport, and a A4 SE and a A4 S-line.
Without exception, we could consistently set faster times on pretty much any test circuit with the 'comfort' trim. The spring and rebound rates on the suspension were so much better judged, and the higher profile tyres were better at absorbing imperfections in the surface, the net effect being that the tyre was in contact with the road surface more of the time.
On a test track or a normal road, hello wheel skitter
The only cars I’ve experienced having problems keeping their tyres in contact with the road have really lacked damping.
The Cayenne is currently on winters 255/55 x 18 & when (if) the weather improves it may go back on to its summers with 275/45 x 19
On the winters it rides much better & although the maximum grip is lower overall there isn't much in it.
Seriously debating getting another set of 18" & putting some summers on them & selling the 19"
On the winters it rides much better & although the maximum grip is lower overall there isn't much in it.
Seriously debating getting another set of 18" & putting some summers on them & selling the 19"
PSRG said:
I’ve just bought a new, automatic supermini for my partner, with a 1 litre (albeit turbocharged) engine generating a heady 115PS. It’s fitted with 18” wheels (which, to be fair were optional...) and shod with 215/45/18 tyres
Pretty sure they are 40 section not 45 looking at the photo. Debaser said:
That sounds rather odd. I've always found the sportier chassis specifications to be faster on track.
Thats the clincher "on track "Nice smooth circuit surfaces as opposed to our normal roads ,
most suspension set ups on European makes are set up for continental roads or the 'ring not our pothole ridden farm tracks .
I guess it depends on the vehicle certainly older cars still look sporty on deeper profile tyres , this is my caterham and it looks good drives excellent on its 60 profile tyres , I guess the problem being not many new cars come with 13 inch wheels as standard , obviously you can run a lot less pressure in your tyre also I run these at 21 cold grumpy52 said:
Thats the clincher "on track "
Nice smooth circuit surfaces as opposed to our normal roads ,
most suspension set ups on European makes are set up for continental roads or the 'ring not our pothole ridden farm tracks .
A car that’s set up to go fast at the ring will be fast on a B road. Nice smooth circuit surfaces as opposed to our normal roads ,
most suspension set ups on European makes are set up for continental roads or the 'ring not our pothole ridden farm tracks .
The Nürburgring isn’t smooth.
The belief that a modern passenger car is too firm to go fast on a typical B road is a fallacy.
IJWS15 said:
IIRC Pirelli want low profile tyres for F1.
The FIA/FOCA don't want them because it will slow the cars down.
13" wheels were mandated to stop brakes from getting too large. What the change would mean is a huge change to the suspension kinematics and the teams don't want that cost. The FIA/FOCA don't want them because it will slow the cars down.
LMPs have large diameter wheels, they go alright.
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