Do larger wider wheels improve traction?

[captint]

Answers on a post card, continuation of sub topic raised in "the Vortech is coming"

[lomoto]

yes . End of now lets talk about something intresting

[mugwump]

No. Start of .

 

Agree on the lets talk about something interesting comment.

[captint]

Then bring it up

 

[ir_fuel]

 

Care to discuss this then?

[mugwump]

But who cares?

 

Glad to see this forum has maintained its level of political correctness that we have all come to love.

[mugwump]

Care to discuss this then?

 

BTW, did you misread the topic? It was about wider WHEELS !

[Removed]

dash and prescience will be along shortly

[Emperor Ming]

Read this guy on the topic of traction wheel size etc.

www.chris-longhurst.com

The answer is proably 'yes and no' A lot could depend on the conditions for instance. Fat tyres easily aquaplane whilst pizza cutters do exactly that ' cut through'.

There is an arguement that talks about 'footprints' and suggests that inside the extremes of tyres the rubber on the surface contacting the road is the same in a fat tyre as a thin tyre if pressure and car weight are the same.

Generally though in dry conditions I would say wider wheels PLUS wider tyres will improve traction.

Ming the thought provoking

[Removed]

from a memorable thread, here's the thoughts of my friend racing engineer (from Italy), with which I agree with 100%

 

""Hi Minel,

 

not so much time for this issue.

 

Let's remind the three reasons why larger tyres offer better traction:

 

1) Less tyre deformation, given the lower specific force tranferred between tyre and the asphalt (higher contact area with the same weigh => lower forces to be transferred). Please remember that the equation T = gc*N holds true only for non-deforming materials, while rubber is an elastomer.... Please, remember to your friends that not only static driving has to be taken into account, and that accelerating and mostly breaking will definitely change the weight trasferred to each tyre, and easily put in trouble your tyre. Almost doubling the weight trasnferred to front tyres under braking (for instance), could easily cause serious tyre deformation on small tyres, while will result in zero to little deformation in a larger tyre. This is important to assure that the correct contact area is constantly at work.

 

2) Better statistical traction, given that the wider covered area allows you to reach some (potential) areas of the asphalt in which the friction coefficient may be better, and then reduces the probability of breaking traction. Just like playng the lottery: the higher the number of tickets you buy, the higher the probability to win. This factor is very important: if you consider a static driving situation, so when little or no tyre deformation is occurring, by using larger tyres you modify your contact pattern from this:

 

*** ^ driving direction

*** |

*** |

*** |

*** |

 

to this:

 

***** ^ driving direction

***** |

***** |

 

This, I repeat, in static situations, when the inflate pressure holds the same, and larger tyres simply modify the contact pattern. Given such change in that shape, you are more likely to find better grip situations, because you are "scanning" a wider area to look for traction. Please think upon this, you'll realise how important this statistical effect.

 

 

3) Last but not least, better tyre construction, since the larger the tyre, the more performing, higly expensive the piece of equipment you are being endowed. Please don't forget that tyres are made by companies, and companies have marketing and customers segmentation policies. You get what you pay for: larger tyres = more expensive, better engineered and constructed. This is a very important point. People think that 225/45 R17 and 245/40 R17 are the same tyre, just different size. FALSE: the construction is different, and if you go further up with the size, also the compounds is modified.

The second tyre in fact is intended to be more performing, and is designed for that. I know this because I've worked for an automotive manufacturer.

 

 

Of these three factors, 2 and 3 are always at work when you drive, while factor 1 comes into play only when you are braking/cornering (or accelerating, if you have a +++hp car) and then you load the tyre with a very higher load if compared to static situations.

 

 

This is true for dry conditions, and this is true for wet road, as you can easily understand. So no way in which on a wet road smaller tyres can give you better traction performances. Think for instance to wet/ winter tyres for cars: are they smaller, or are they just the same size, with different compound and different design? If reducing the size of the tyre could help traction on wet roads, why tyre manufacturers are not doing that? They could save money also, since smaller tyres are less expensive, both in materials and manufacturing costs, and increase profits!

Think to F1 intermediate tyres, whicy are used for from mid to wed conditions: are they smaller? C'mon, don't waste time on that....

 

 

 

All of this becomes false only when you shift from "wet" conditions to "flooded" conditions, and then the real enemy becomes aquaplaning. In that situation, the larger the tyre, the more easily it will become a "surf board", and as speed rises, you'll start doing surfing, instead of driving

That's why in rallies and other competitions on mud and snow (have you ever seen motobikes' races on ice?), they use very very small (spined) tyres, because in this way the lower contact area allows the tyres to penetrate into the water / mud even at high speed. Of course, the lower surface decreases traction performances, but at least you have some traction, since you are not flying on water / mud / snow, but you are touching the ground.

 

 

But who cares about this???

Have you ever experienced real aquaplaning? I have, and from then on, at least as far as I'm at the wheel, when I see the road conditions turning into potential acquaplaning, I slow down, and not start arguing about my tyres size. I'm not a professional driver, and moreover my car is tuned for dry road (wheels, suspensions, boost gain pattern, everything is tuned for dry).

Eventually, even F1 rain tyres are not much smaller than slick, just highly sculpted in order to drive out the largest possible quantity of water.

 

 

 

That's why I strongly suggest not to get involved in this kind of discussion which are really a waste of time. Discussing about cars and mechanincs, in my opinion, is good as far as it helps you understand something useful for your driving experience. I saw your forum, 9 page discussion for this is.... unbelievable.

 

 

Hence:

1) If someone thinks that smaller tyre will give him better traction on dry or wet conditions, leave him to his (probably bad) fate;

2) If someone thinks he should use smaller tyres so as to have less chance for aquaplaning, I'd rather suggest him to slow down when it starts raining hard, and keep larger tyres for all the rest;

3) ...and save your precious time to work and earn your TT upgrade

 

 

All my best,

 

Miraglio"

[captint]

Well put that way, I'm going for 19's, I was thinking 245 - 255 on the front and 285 - 295 on the back.

[ir_fuel]

295? Does that fit?

[captint]

It bloody wants to

[Liam's Z]

Good guide for calculating wheel sizes - originally passed onto me by Dorian

 

http://www.torquecars.co.uk/Tuning/alloy-wheels.php

[Kev946]

I wish I had gone for a 255 on the front. The 245/35 x 19 option does have a smaller rolling radius than the standard 18 inch wheel, so this does put extra streaa on the front suspension and creates more road noise. I spoke to the guys who supplied my wheels whilst I was in LA and he had 255's on his Zed. He said he started on 245's and changed them before they even wore out. I wish he's have said that to me before I ordered them. Anyway you live and learn.

 

He was running 255/35 x 19 and 285/35 x 19 with 9.5 fronts and 10.5 rears. His car was setup for drifting..

[mugwump]

I wish I had gone for a 255 on the front. The 245/35 x 19 option does have a smaller rolling radius than the standard 18 inch wheel, so this does put extra streaa on the front suspension and creates more road noise. I spoke to the guys who supplied my wheels whilst I was in LA and he had 255's on his Zed. He said he started on 245's and changed them before they even wore out. I wish he's have said that to me before I ordered them. Anyway you live and learn.

 

He was running 255/35 x 19 and 285/35 x 19 with 9.5 fronts and 10.5 rears. His car was setup for drifting..

 

Hi Kev, I am confused by your post (easily done). The 255 or 245 relates to they tyre width? So why does this impact the rolling radius?

 

I can understand that a tyre on a 19" wheel has a reduced sidewall which will produce the effect you describe (more noise and stress) but what has this to do with the width? or did I miss something?

 

Just after clarity because I want to go to 19"s (or maybe even 20"s) and the benefit of your experience would be great.

[Gus]

Mugwump,

 

The overall diameter of a wheel plus tyre, is the diameter of the wheel ( say 19" ), plus twice the depth of the tyre sidewall.

 

When a tyre is 245*35*19, then 245 is the width, 19 is the wheel size, and 35 is the aspect ratio ( in percentage ).

 

Aspect ratio of 35 means 35% of the width, ie the depth of the sidewall is 0.35*245 = 85.75mm.

 

It them follows that 255*35*19 will have a different sidewall ( 89.25mm ), and therefore different overall wheel+tyre diameter ( 7mm difference ).

 

Gus

[lomoto]

I wish I had gone for a 255 on the front. The 245/35 x 19 option does have a smaller rolling radius than the standard 18 inch wheel, so this does put extra streaa on the front suspension and creates more road noise. I spoke to the guys who supplied my wheels whilst I was in LA and he had 255's on his Zed. He said he started on 245's and changed them before they even wore out. I wish he's have said that to me before I ordered them. Anyway you live and learn.

 

He was running 255/35 x 19 and 285/35 x 19 with 9.5 fronts and 10.5 rears. His car was setup for drifting..

 

Hi Kev, I am confused by your post (easily done). The 255 or 245 relates to they tyre width? So why does this impact the rolling radius?

 

I can understand that a tyre on a 19" wheel has a reduced sidewall which will produce the effect you describe (more noise and stress) but what has this to do with the width? or did I miss something?

 

Just after clarity because I want to go to 19"s (or maybe even 20"s) and the benefit of your experience would be great.

 

your quite correct 245 and 255 equates to tyre width, but if the aspect ratio of 35 is the same ,the 255 width tyre will have a higher side wall ie larger dia than a 245 tyre, thus larger rolling radius,

 

thought I'd just answer in case Kev's not kicking about

 

 

[edit]oops too late gus got there before me

[mugwump]

Aha! Thanks chaps, all makes sense now.