Most ridiculous size tyres on car

[Kozy]

Further to my post up there:

BMW X5 on 315s?

500kg per wheel, 315mm section width. 315/500 = .63

BMW X6 on 335s?

525kg per wheel, 335mm section width. 335/525 = .63

Vauxhall Adam on 225s?

Assuming 65% front weighted and 1100kg, that's .63 at the front and 1.17 at the back, but that's fairly standard of FWDs.

So, it stands to reason that my 185 section tyres are in fact quite ridiculous at .75 'width to weight' ratio, compared to some really rather middle of the road suggestions here...

[Sparkov]

E65Ross said:

a thinner tyre given the same tread pattern WILL give less rolling resistance and I'm willing to bet that the 155 section tyres will have less rolling resistance than the 2xx wide tyres fitted to most cars on the road

the 19s look ridiculous in your opinion. I, and many others, think they look just fine on the car. It's the rest of the car I have issues with

Actually the opposite is true; a thinner tyre will have more rolling resistance than a wider tyre at the same inflation pressure. The contact patch is longer and slimmer and imparts more radial deflection on the tyre sidewall.

[HustleRussell]

Sparkov said:

E65Ross said:

a thinner tyre given the same tread pattern WILL give less rolling resistance and I'm willing to bet that the 155 section tyres will have less rolling resistance than the 2xx wide tyres fitted to most cars on the road

the 19s look ridiculous in your opinion. I, and many others, think they look just fine on the car. It's the rest of the car I have issues with

Actually the opposite is true; a thinner tyre will have more rolling resistance than a wider tyre at the same inflation pressure. The contact patch is longer and slimmer and imparts more radial deflection on the tyre sidewall.

I stand to be corrected but I thought that with radial tyres, given the circumference, pressure and load are the same, the difference in the shape of the contact patch is near negligable due to the belted construction of the tyre?

[Flying Toilet]

GC8 said:

Flying Toilet said:

I cant read the text, but they look like Porsche 928 S4 seats in the front, although that isnt a Porsche colour.

Correct on all counts.

[HustleRussell]

Oh and also, Efficiency isn't just about rolling resistance but air resistance too- and a narrower tyre has a lower frontal area which is good for air reststance.

[E65Ross]

Sparkov said:

E65Ross said:

a thinner tyre given the same tread pattern WILL give less rolling resistance and I'm willing to bet that the 155 section tyres will have less rolling resistance than the 2xx wide tyres fitted to most cars on the road

the 19s look ridiculous in your opinion. I, and many others, think they look just fine on the car. It's the rest of the car I have issues with

Actually the opposite is true; a thinner tyre will have more rolling resistance than a wider tyre at the same inflation pressure. The contact patch is longer and slimmer and imparts more radial deflection on the tyre sidewall.

you know what i mean, and it's not the case. If it were, how come my road (pedal) bike rolls much better on thinner tyres than wider ones? are you saying a car would have less rolling resistance if it had 2 tyres which are 500mm wide than if it had 2 identically-treaded tyres which are 150mm wide? if so, you're wrong.

[Sparkov]

E65Ross said:

you know what i mean, and it's not the case. If it were, how come my road (pedal) bike rolls much better on thinner tyres than wider ones?

I do know what you mean, and agree that it's not very intuitive, but it's been proven to be the case. Your road bike will only roll better due to decreased tyre rolling resistance from thinner tyres if you have the pressure significantly higher:
http://www.schwalbetires.com/tech_info/rolling_res...

[Sparkov]

E65Ross said:

you know what i mean, and it's not the case. If it were, how come my road (pedal) bike rolls much better on thinner tyres than wider ones? are you saying a car would have less rolling resistance if it had 2 tyres which are 500mm wide than if it had 2 identically-treaded tyres which are 150mm wide? if so, you're wrong.

I replied before your edit, and yes the wider tyres would theoretically have less rolling resistance due to tyre deformation if the pressures were the same. That doesn't mean that the car would run more efficiently because I'm sure that the increased aerodynamic drag and extra weight would have a far greater effect to the contrary.

[Vladimir]

22Rgt said:

Part of the Special Air Service, seven years 22Rgt B Squadron and proud. Proud being the word here, not boastful, just proud..

I know exactly what it is but my exposure to the SAS is limited to throwing stuff at them for riot training. We all cacked ourselves.

[Shambler]

kmpowell said:

Shambler said:

I realise that most cars these days come with wide tyres but was surprised when shopping for a diesel estate. The Audi A6 s line 2.0 tdi comes with 255 profile tyres which seems ridiculous.

rallycross said:

anyone running a road car with 30/35 or 40 series tyres on anything other than a supercar is a muppet.

Interesting... I fall into your categories of 'ridiculous' and 'muppet', as my 2.0TDi S-Line Avant is specced with the 20" rotors shod in 255/35/20 rubber.




I'm not sure how me buying something that was supplied by the factory/brand categorises me in that way, especially as the wheels [in my opinion] suit the car well and don't look out of proportion to the rest of the car. If I was driving around in the aftermarket/replica A3 mentioned previously in this thread, then maybe, but your generalisations above perplex me, somewhat, for my situation...


My point was the width of the tyres for the type of vehicle. I would think that 205 tyres would be more than enough and probably a lot easier to drive in bad weather (snow for example)

Edited by kmpowell on Wednesday 20th November 11:30

[E65Ross]

Sparkov said:

E65Ross said:

you know what i mean, and it's not the case. If it were, how come my road (pedal) bike rolls much better on thinner tyres than wider ones?

I do know what you mean, and agree that it's not very intuitive, but it's been proven to be the case. Your road bike will only roll better due to decreased tyre rolling resistance from thinner tyres if you have the pressure significantly higher:
http://www.schwalbetires.com/tech_info/rolling_res...

well yes but that goes without saying doesn't it? People stick to what the manufacturers say the tyres should be pumped up to (or rather, they should) so saying that as an argument may be true but is largely irrelevant, no?

[Fox-]

kmpowell said:

Interesting... I fall into your categories of 'ridiculous' and 'muppet', as my 2.0TDi S-Line Avant is specced with the 20" rotors shod in 255/35/20 rubber.

Whats the point? I'd rather have opted for one with a decent engine shod on 17's and spent the saving on tyres on fuel instead.

2 litre TDI engines are a compromised choice made in the name of low running costs - so why undo that by fitting it with 20 inch wheels?

[Vladimir]

Fox- said:

Whats the point? I'd rather have opted for one with a decent engine shod on 17's and spent the saving on tyres on fuel instead.

2 litre TDI engines are a compromised choice made in the name of low running costs - so why undo that by fitting it with 20 inch wheels?

Me too.
Massive wheels may be seen as cool but tiny little brake disks lost behind them most certainly are not...

Edited by Vladimir on Wednesday 20th November 18:23

[Crombers]

285/35/21 on the 7 Series whilst retaining a fantastic ride quality (and an element of capability in the twisties ).

[CoolHands]

kmpowell said:

Shambler said:

I realise that most cars these days come with wide tyres but was surprised when shopping for a diesel estate. The Audi A6 s line 2.0 tdi comes with 255 profile tyres which seems ridiculous.

rallycross said:

anyone running a road car with 30/35 or 40 series tyres on anything other than a supercar is a muppet.

Interesting... I fall into your categories of 'ridiculous' and 'muppet', as my 2.0TDi S-Line Avant is specced with the 20" rotors shod in 255/35/20 rubber.




I'm not sure how me buying something that was supplied by the factory/brand categorises me in that way, especially as the wheels [in my opinion] suit the car well and don't look out of proportion to the rest of the car. If I was driving around in the aftermarket/replica A3 mentioned previously in this thread, then maybe, but your generalisations above perplex me, somewhat, for my situation...

Let me help you. You fall into the category of 'ridiculous' and 'muppet'. It's that simple. Just because your car came like that as specced isn't a get-out-of-jail card - they're ridiculous. It looks cack too (obviously, IMO). It's a diesel estate car - why does it need 255 tyres?

BTW I believe 'rotor' referres to the brake disc, but I perhaps I've been outdated

[CoolHands]

Whoah hold-up - I've just noticed it's an 'S-line' whoo

[E65Ross]

Crombers said:

285/35/21 on the 7 Series whilst retaining a fantastic ride quality (and an element of capability in the twisties ).

Surely then the tyre size isn't ridiculous? Or am I missing something?

[kmpowell]

Fox- said:

I'd rather have opted for one with a decent engine shod on 17's and spent the saving on tyres on fuel instead.

2 litre TDI engines are a compromised choice made in the name of low running costs

You do realise that's a subjective statement you've made?!? Without wishing to sound vulgar I can afford an RS6/S6/Bi-Turbo/3.0, but in the real world the 2.0 is a, in your words, 'decent' engine that does the job perfectly for my circumstances. As mentioned above, I bought it lightly used, so I didn't have to pay the ridiculous £1800 for the 20" upgrade, and as part of the deal they put on 4 brand new tyres which will serve me the time I own the car, proving I don't get a puncture, this negates any comments re economy. Your point re the brakes, again, is subjective, because quite frankly I couldn't care less what the brakes look like.

I'm still none the wiser why some people think that fitting low profile tyres to anything other than a supercar, is ridiculous...

[E65Ross]

just out of curiosity, does the tyre width also need to be wider for heavier cars (as someone posted above). If so, it makes sense that cars are getting wider tyres whilst not necessarily getting more power.

[kmpowell]

CoolHands said:

It's a diesel estate car - why does it need 255 tyres?

Nowhere have said it does need them, I'm asking why fitting them to car makes it, in some peoples eyes, ridiculous?