Grip

Andy_S

Andy_S

I Love Booooooost!
Club Member
Have a question about grip on the road.
When its dry my car handles like a go-cart. But when its wet i turn the wheel a bit and it just slides. WHen i set off in wet and set off nice and easy it wheel spins. I got 2 new tyres on about 2 months ago and i cant understand it.

Any idea's?

Cheers
 
you're not taking it easy enough

Poor quality tyres
Excessive weight at rear of vehicle causing front wheels to lift very very slightly just enough to break the traction
 
Thats just how they are mate.....in the wet your better with steelies...because alloys are wider the water can get under your tyres more than a normal steel wheel....i cant really explane it...but its like in snow...the best car in snow i would say is an old Mini cooper...because the tyres are thinner they cut thro the snow rather than Pushing it like a normal alloy would. The new tyres you have on could be a harder rubber aswell so when there cold it would be like having plastic tyres on :)
 
Cheers guys. The front Tyres are Ceat 195/45/15 and were supplied and fitted at Kwik Fit.

easy enough haha i have to set off at about 1000RPM and slowly get upto 30mph. i cant get to 10mph and put more gas on cause it just shoots to 6k rpm wheelspinning.
 
Andy_S said:
Ceat.
Click to expand...
that seems to be the problem lol. try using a brand of tyre designed for the rain. falcon 512's arnn't too bad also kumho ecsta sports. don't know if you can get uniroyal rain tyres in your size, i had some of these and they was v. good.
 
I've heard the Good Year Engle F1's are the best for wet weather - I'm looking at getting a set but 15" 45 profile will set you back about £55 a corner!

Alot better than the kwik fit stuff!
 
Alienfish360 said:
you're not taking it easy enough

Poor quality tyres
Excessive weight at rear of vehicle causing front wheels to lift very very slightly just enough to break the traction
Click to expand...

Poor quality tires are a possibility

...that 2nd reason is not a possibility. If you reduced weight from the front this would be plausable..

However - Extra weight over the wheels would reduce wheel spin

But

Extra weight in the car generally would exaggerate wheel spin...

...what you want to do if at all possible is either reduce weight in the car or move weighty things from the back to over the front wheels...Again this is impractical..

Theres nothing you can do other than change your driving style or use WIDER tires...

5ilver Micra said:
in the wet your better with steelies...because alloys are wider the water can get under your tyres more than a normal steel wheel....
Click to expand...

This is not true...

What you said about thinner tires having more control in snow is true to a degree.. Snow is a semi solid and ICE is a solid... in ICE your better off with 'studs'.. regardless of tire width..

Snow is a trickier one to explain, it comes down to how compacted it is.. the more its been driven over the more it takes the charicteristics of ICE..

Using Thinner tires in the wet will greatly exaggerate wheel spin. Do not do this...

The ONLY occasion that a thinner tire will have the edge over a much wider tire is at considerable speed over standing water.

Refered to as AQUA PLANING. This is down to the sheer speed of the car and how deep the water is... in lamants terms the a car can effectively WATER-SKI given enough speed and deep enough water.. The faster the car is going the less water it takes to 'elivate' the car...

From a standing start like ANDY_S is refering to and general slow speed ( 40mph ) cornering as wide a tire as possible is the best bet.. a car will not auqaplane at these speeds.. you need to be in excess of 60-70mph to do this with a commonly used lo-profile tire.
 
well mine can slide when turning a corner at 20-30mph. Kristian i shall show you what i mean next time i down and its wet.
 
Kristian, it sounds like you are bias toward having the widest tyres possible, wider does not always mean better, Silver Micra is true in his statement.
 
There's good points to any kinda tyre, budget tyres are good too but if you plan to push your car to the extreme which I suspect you do at time then money needs to be spent on some good rubber
 
Agree with the thinner comment posts. I had some 195/45/15's (toyo T1-Rs) on the ST, in the wet its terrible especially once the tyres are at half their life. At any normal speed the simply is not enough weight to push the water out of the way. I currenly have a Renault 19 TD as a work car and its much much heavier at the front. It is MANY TIMES better in the wet than the ST (using the same tyres). Also a standard K10 with stock steel thin tyres is also MUCH better in the snow than the ST with 195's on. (which to be honest was terrifying)
 
silver_si said:
that seems to be the problem lol. try using a brand of tyre designed for the rain. falcon 512's arnn't too bad also kumho ecsta sports. don't know if you can get uniroyal rain tyres in your size, i had some of these and they was v. good.
Click to expand...

ZE512's have good dry and wet grip and also pretty good water dispertion but the sidewalls are like jelly.

They might be ok in 195/45r15 because of the tiny sidewall, but in 185/55r14 its terrible. I'm too scared to push them to the their traction limits - I'm worried they'll roll over and peel off the rims!

Excellent ride quality though. :laugh:


But yeh, quality tyres is a must.

A few of the guys here use Yokohama A539 and reckon its like they can't tell when its wet - but they use them on 13's mainly in the standard super s size 175/60r13.

I must say that driving a whiteline-kitted k11 in the wet with nexen n2000 185's is like being on skates... Understeer as you enter the corners, throttle off or trail brake and you get oversteer as well. If you're really unlucky you can 4 wheel drift through roundabouts.:laugh:
 
Yom said:
ZE512's have good dry and wet grip and also pretty good water dispertion but the sidewalls are like jelly.

They might be ok in 195/45r15 because of the tiny sidewall,
Click to expand...
i had these on my corolla in 205/40 17, so never experienced jelly walls. lol.
 
I agree that the wider the profile the tyre the worse the grip will get in adverse conditions, this is regardless of speed, weight distribution or water depth on the road, in my experience narrower tyres are better for wet/slippy conditions, and wide tyres are best suited for dry conditions, in my 25 years experience on the roads in wet/slippery conditions I have never found anything better than Uniroyal Rallye tyres.
 
Its very easy for everybody to point out their own personal expeareances with tires and conditions and grip.. this would hardly be a realistic concensus.

If you would like to get technical..

What you are looking for for grip is friction.
The HIGHER the coefficient of friction the more grip the tries will have.

There are varying factors involved on working out your coefficient.

The MAIN one to apply is PRESSURE.
"QUOTE"
The amount of frictional force is proportional to the surface area of contact, but it is also proportional to the pressure with which the two surfaces are "pressed" together.

If you increase the surface area however, you will by definition decrease the pressure since pressure is "weight divided by surface area." So a change in surface area will cause two counterbalancing effects.
''unquote''

Like I said earlier with the weight dritribution.

The wider the tire, the less pressure the tires will apply to the road, BUT The Wider the tire the higher the coefficient of friction...basically theres more rubber to grip...

SO what it boils down to - Is if the loss of grip ( due to reduced pressure ) with using a much wider tire is COMPENSATED with the gain in grip with using a larger tire ( more area )...

Where in the realworld the only variable with pressure that can really be concidered is weight.. And car has a LOT of weight in relation to the 'total area of Rubber' on the road...

I could go into much deeper detail but I cannot be bothered..

Some of you are talking about AUQAPLANING but this is non existant at <60mph speeds...

If you need visual proof in addition to my theoretical,

Look at any motorsports... In motorsports where racing in the wet is as common as racing in the dry do they slap on some really THIN tires for that extra grip?

No..

They simply adopt tires with 'tread' to help displace the water. Width mostly being the same.. Never less...
 
Kris, you are 100% right...

am currently on tyre construction as part of Vehicle design unit at uni.. and you pretty much got all that info bang on... especially about the thread gaps to displace water and give grip...

as for the aquaplaning thing, thinner wheels may be more controlable during aquaplaning than wider ones but that is a totaly different argument... wider wheels may reduce the chance of aquaplaning, but once your in the predicament wider wheels will surf over the water...
 
all the big brands

Dunlop, pirelli, Continental... etc

Some of the performance brands are probably your best bet... FALKEN - TOYO etc...
 
kristian said:
all the big brands

Dunlop, pirelli, Continental... etc

Some of the performance brands are probably your best bet... FALKEN - TOYO etc...
Click to expand...

Continental = nono...yes they will last years but the tyrewalls crack very easily..ive lost count on how many continental tyres ive changed because of this....Never low on tread tho.

Btw....have you noticed in motorsport when its 'wet' they allways wheel spin at the start until they reach higher speeds because of the Spoiler Downforce..
so unless your driving around town at 60-70mph every where i would stick with steelies for the winter...Im not saying that your wrong Kristian but im jus saying that with wider tyres your more likely to slip and slide.fwn
 
5ilver Micra said:
Btw....have you noticed in motorsport when its 'wet' they allways wheel spin at the start until they reach higher speeds because of the Spoiler Downforce..
so unless your driving around town at 60-70mph every where i would stick with steelies for the winter...Im not saying that your wrong Kristian but im jus saying that with wider tyres your more likely to slip and slide.fwn
Click to expand...

You are not reading what I am typing...

Thinner tires will provide LESS grip in the WET!

..FACT..

what you said about wheelspin in motorsport is true, given thinner tires they would wheelspin more... irrelivant of speed...
 
kristian said:
You are not reading what I am typing...

Thinner tires will provide LESS grip in the WET!

..FACT..

what you said about wheelspin in motorsport is true, given thinner tires they would wheelspin more... irrelivant of speed...
Click to expand...

I am reading what ur typing......Its just when you split the weight on to a bigger surface means there is less pressure on the ground....where as a thinner wheel sort of means there is More pressure on the ground from the tyre....Obviously you know what you talking about but i have been in my mates ford ka in wet with his 15' alloys and his 13' steelies and the steelies handle Much better fwn
 
If you put 1'' wide tires on the car.. I bet there would be loads of pressure.. meaning loads of grip???!?

what your saying is correct, however what you need to understand is that there is more pressure over a ''smaller area''.. Pressure is in relation to weight.

The pressure increase is negligable in comparison to the Grip increase when wider tires are used
 
Im quite confuzed now :grinning: Ofc when its Sunny and (no rain) there will be more grip on a wider tyre...Tread is only there for the Rain anyway...but i dont see why my mates car handles like my Scoot does in the rain (rubbish) with alloys And why it grips like a Magnet on steelies? o_O
 
Maybe its got something to do with the tyres you have on the rims.

Not all tyres are created equal either - sometimes you can get different batches which may not be as good as the last batch (the goodyear eagle F1 is one tyre I know that this happens alot. There's a number of different F1's that used to be available in australia. They were german (?? somewhere in europe anyway) made examples, thailand made examples, japan made examples and a USA/mexico made example if i remember rightly and the best pick was the jap made F1 despite it wearing down quicker than the other country examples).

Heck, some tyres are better in some sizes than they are in another size too.
 
Back to the beggining, ceat tyres are cheap and arent to great in wet. As far as presure applied in relation to width of the tyre (not profile this is the "height of the bead(the area from the rim to edge of tread)) the presure is the same. Are you not applying the same amount of force/weight???

With wider tyres the presure is more spread out and able to find traction better but in turn increases drag at high speed. Thinner tyres cant find traction as easily but therefore have less drag.

Thinner tyres through snow is working on theory that the tyres will cut through the "soft" snow to possibly ice (using studs) or tarmac depending on conditions.

For good grip on dry you want a tyre with a soft rubber, they where quicker but grip better! The thumb rule for this is more expensive, softer the rubber!

As for the 13' better than 15's best i can come up with is a higher profile and more role, not what you on dry but works better in wet! Hence rally tyres have high profile.

Yes uniroyals have always been the best rain tyres, but thats about all they are good at personally!
Slap some sexy Goodyears on!
 
There is so much more to it than just the make of tyre, the tread pattern, tyre pressure, compound etc.

In the dry you generally want a wide, low profile tyre for tarmac use, this gives a good contact patch and less deformation when the wheels are turned due to the low sidewalls.

For the wet you want a thinner tyre as it cuts through the water much better to get to the grip below. If you have a wide tyre on it tends to glide over the water and aquaplane.

And rallycars use such a high side profile on there tyres on gravel so the tyre acts as a means of suspension aswell and due to the tyre itself being thick to help avoid punctures. All that is from people who have been competing in motorsport for the past 20 years or so.
 
From Motorbooks "High Performance Handling Handbook"-Don Alexander:

"Most original-equipment tires have a compromise design, allowing good traction in both wet and dry conditions. These tires have tread patterns that work well in the wet but reduce steering responsiveness in dry situations. High and ultra-high-performance tires have softer tread compounds and much more aggressive tread patterns, which usually mean a lower void ratio (the area of the grooves at the contact patch versus the area of rubber at the patch). Higher void ratios mean more resistance to hydroplaning but less rubber on the ground. Original-equipment tires have higher void ratios, while performance ...tires...have smaller void ratios.

"Wet traction is influenced by the tread compound as well. ..."

"Wider tires are also less resistance to hydroplaning as well. More rubber on the road, whether from greater section width or lower void ratio, means more hydroplaning."

So, wider tyres and lower void ratio at the contact patch equals better grip in the dry but not the wet (usually, but depends on quality of tyre).

The thing is, you shouldn't by a tire by looks, price or what's in vogue at the moment and expect it to perform well under all conditions. You need to do some research. "Which" magazine and several of the car publications often run comparison tests. In the last "Which" test, for instance, certain Bridgestone, Continental and Micheline tyres all received the highest rating under both wet and dry conditions. Uniroyal scored high in the wet but only so so in the dry, and didn't do at all well in the wear department.

You pays your money and you takes your choice. But do your homework first.



S
 
I have read all of this now. Here is what I know from studies.

Firstly, coefficient (coeff) of friction may not be understood by all. The coeff. of friction is defined by this equation:

F =μ/r

r=is the reaction force, this is basicly the weight but in Newtons=weight*gravity(9.81)

μ=This is the greek symbol mue, and is the symbol meaning coefficient of friction.

F=is the maximum friction force opposing movement, so if you were pushing a block, the friction stopping you just before the block moves is F this F is basicly the same as what ever force you input, untill you have motion and then F is less than the input force.. Maybe it means he is called frank hahaha.


There are 2 types of coeff. the first is the static coef. this is the maximum frictional force that will oppose motion (Fmax), so again, if you push a block, the coefficient of static friction can be 0 to Fmax, once the force excedes Fmax the block will move, and then you have cooeficient of dynamic friction also known as the cooeficent of kinetic friction. When your cars still, the coefficient of static friction is keeping it there, when its moving the coefficient of kinetic friction is opposing its movement.

coefficient is a ratio, this means it has no units, it is a value between 0 and 1, 0 being no friction at all, you would slide infinatly, 1 is absolute friction, you wouldnt be able to move at all.


Firstly, some misunderstood opinions stated above may lead to confusion.

kristian said:
What you are looking for for grip is friction.
The HIGHER the coefficient of friction the more grip the tries will have.
Click to expand...

This is correct, the higher the cooeficent of friction the greater the grip.

kristian said:
The Wider the tire the higher the coefficient of friction...basically theres more rubber to grip...
Click to expand...

I'm affraid this is wrong, as you can see from the equation, the width of the tyre has nothing to do with the coefficient.


kristian said:
Some of you are talking about AUQAPLANING but this is non existant at <60mph speeds...
Click to expand...

Refered to as AQUA PLANING. This is down to the sheer speed of the car and how deep the water is... in lamants terms the a car can effectively WATER-SKI given enough speed and deep enough water..
Click to expand...

Aquaplaning is when a car brakes, the wheels lock and the surface water goes underneath the wheels, the car then slides along a very thin layer of water, going into an ice like skid. Deep water wouldnt cause aquaplane, its more likely to occur on roads with surface wetness. Aquaplaning can occur at speeds around 20mph, not just at over 60, if you locked up on a wet road at 20mph, you could still aquaplane.

Extra weight in the car generally would exaggerate wheel spin...
Click to expand...

Extra weight would increase the R in the coefficient of friction equation and therefore increase the coefficent. So more weight would increase grip. You dont see the challenger tank drifting around donnington because its heavy and so has lots of grip. But on your theory it would be sliding around.

In conclusion


Wider tyres are right for dry roads, as there is a greater area of surface contact, so obviously there is more area for frictional force to do its work, frictional force is different to that of the coefficient, the coefficient is how slidy a material is to put it simple, so you have the slidynes ratio and then you have the area its spread across, the weight, the temperature, the surface its against, all of these and many more make up the actualy finishing frictional force.

However in the wet its a completely different. The wider tyre will offer more grip in the dry, but in the wet the width of the tyre affects its ability to grip. Since the water will be hitting the forward edge of the wheel, and the grooves in the wheel will move this water to the edge. With a thinner wheel, the water is quickly moved away from the forward edge, but with a wider wheel, the water builds up in the grooves and stops them from doing their job. The pressure of water under the wheel then increases, once you apply any kind of forward or breaking force, the pressure will increase more, make the car more inclined to aquaplane. So the wider wheels will have more grip, but because they are essentialy running around with a alot of pressured water under the wheel, they never actualy get to use the grip. They are constantly fighting against skiding.

I hope this was informative for all.
 
Some excellent posts here. I can post my factual experience on this too.

Several years ago, in the Black ST traveling SW, over the Exeter Tymar crossing (North, not South) there is a slight uphill slope. Not anything to really bother anything about. However at this time the ST had 195 profile tyres on it and only about 2mm tread depth, it had just been raining. The ST is usually very bad anyway (only 250KG per front wheel) and in this case it was impossible to drive at anything more than 30-35mph. There was simply no traction on the front wheels from the water on the road (only a few mm) Infact I had to slow down to the point where a lorry decided to pass. Equally however in the dry they were capable of generating 1.05G of breaking force. Of all the cars I have driven light FWD cars suffer in my opinion the greatest swing from grip to slip on changes of road condition. It is for that reason that I'm so carefull when I feel the roads may be damp etc.
 
mine too haha. either pirrelli p7 or goodyear egal F1 i going for. £1.** diff in price per tyre anyway.
 
the p7 are good all rounders like most pirrellis where as good years tend to be better dry as they have quite a soft sexy compound which are better on dry!
 
Bazraf said:
However in the wet its a completely different. The wider tyre will offer more grip in the dry, but in the wet the width of the tyre affects its ability to grip. Since the water will be hitting the forward edge of the wheel, and the grooves in the wheel will move this water to the edge. With a thinner wheel, the water is quickly moved away from the forward edge, but with a wider wheel, the water builds up in the grooves and stops them from doing their job. The pressure of water under the wheel then increases, once you apply any kind of forward or breaking force, the pressure will increase more, make the car more inclined to aquaplane. So the wider wheels will have more grip, but because they are essentialy running around with a alot of pressured water under the wheel, they never actualy get to use the grip. They are constantly fighting against skiding.

I hope this was informative for all.
Click to expand...


This is what i was trying to say....but im not very good with words :D why didnt you quote any of my words :(
 
Bazraf said:
Extra weight would increase the R in the coefficient of friction equation and therefore increase the coefficent. So more weight would increase grip. You dont see the challenger tank drifting around donnington because its heavy and so has lots of grip. But on your theory it would be sliding around.

QUOTE]

I was reffering to extra Mass... I.e Not the weight over the wheels.. Remember that these cars are not 4WD.


The extra weight over the rear wheels would be classed as a DEAD weight not included in you 'r'

Your 'correction' over auqa planing is a disagreement in terminology. Im talking about lack of steering at higher speeds, your talking about the coefficent being reduce due to a water film not being displaced while breaking,

Very different things..
Click to expand...
 
all this about aquaplaining ect meh all i know is it doesnt matter what you do to you car the only things that touch the road are the tyres!! scrimpin on them is not an option!! i run dunlop F1's love the to bits i won't be using another tyre make again, they are quite soft though . but i will put some steelies on if it snows.. cos 195's will just float on snow.. 155's i might get some grip or at least be able to dig down to the snow wth them!!
 

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