Tyre brands

[MULLEY]

165/70's i didnt think anyone still fitted them to the bx Allright in the dry, but in the wet

[DavidRutherford]

165/70's i didnt think anyone still fitted them to the bx Allright in the dry, but in the wet they tend to cut through standing water, and hence are less likely to aquaplane. They're also the correct size for most models, and are a bit safer, as the car will tend to break away progressively, rather than grip and grip and grip and then break away suddenly, leaving you upside-down in a ditch.

Quoted for accuracy.

Just because you have 165 tyres doesn't mean you're going to get bad handling. I'd say that good quality 165's are massively better and a lot safer than cheapo 185's

Granted, the BX is a little under-tyred, but fitting wide grippy rubber just means that the eventual break-away is less controllable.

[MULLEY]

I'm not convinced that narrow tyres would cut through water as some of the factors in water dispersal is the tread pattern & the width of the tyre, the more tread & the wider the tyre, sureley it clears more water.

I do agree though, that a high quality narrow tyre would outperform a nasty 185/60.

I also agree to a degree that you would get potentially safer understeer on the narrow tyre, but then again if you go into a ditch, then perhaps its not the tyres fault in anycase

[Philip Chidlow]

I find discussion about tyres always interesting (saddo)... and there are as many different views about tyres as there are brands.

A 165 will be better in snow and water that's lying on the surface at a point (maybe a couple of cms) where the tread is overwhelmed. Or so I have been told. The GSX had 145 profiles and that worked fine on loose road surfaces in France (they do love chucking loads of gravel about) but in the dry, on a bend where less good. The TGS I had was shod with 165's and they were 'OK' but in the dry, damp or 'normal' wet, nothing I've experienced beats a Pirelli P6000 185/60 (GTi) or a 195/60 Kleber (16V) on a BX.

[jonathan_dyane]

I'm not convinced that narrow tyres would cut through water as some of the factors in water dispersal is the tread pattern & the width of the tyre, the more tread & the wider the tyre, sureley it clears more water.

Tyre size and usefulness in adverse conditions is a tremendously interesting subject, although somewhat complicated, and I certainly would not claim to know any of the theory, but do believe that a wider tyre will be more likely to be 'floated' by the water rather than 'cut through' as David notes. For years I drove 2CVs and Dyanes, usually pretty hard, and found that with their skinny Michelin 125 tyres one could drive through standing water and corner in the wet at higher speeds than most normal cars. This was most noticeable on roundabouts, where I would hurtle round at my normal speed, and other cars were often seen to slide trying to compete.

I suppose that the first years of my driving career driving A-series coloured my judgement of what good roadholding and handling is, but I feel most confident when driving a car which clearly shows me where it's limits are, and once reaching the point at which grip is lost progressively break away into understeer/drift/oversteer. In the course of work, having driven many modern cars, which are typically very 'overtyred' I have discovered that none of them have either the feeling of nimbleness, accuracy or control, nor the progressive loss of grip that narrower, higher profile tyres can permit.

As such, although fatter tyres clearly can and do provide better grip up to a point, they can mask the deficiencies in the basic suspension design of the vehicle, and when the limit is reached react violently with little warning, in such a manner that unless you have superb reactions and know what you are doing very bad things will happen.

One final point in favour of the 'skinnier' tyre; higher profile tyres give a more comfortable ride!

[DavidRutherford]

the wider the tyre, sureley it clears more water.:

The narrower the tyre, the less water it has to clear.


Also, with narrower tyres and the same weight of car, the ground pressure is much greater, hence better contact between the tyre and the road. This manifests itself in a higher speed needed to achieve aquaplaning. I proved this with one of my old Horizons. The 145 section tyres were generally a bit narrow, but the car was almost incapable of aquaplaning. Changed them for some 195 tyres on alloy wheels, and it was then much more susceptible to going very drifty over standing water. So much so that I changed back to the 145's and just put up with the worse handling in the dry.

[MULLEY]

Interesting points raised by club members. I do agree with the snow though, narrow tyres are ace, low profiles are just plain useless.

I think one of the factors is the weight of the car, which has been pointed out, but quite how anyone can draw conclusive information about whats ideal is probably impossible.

The way i was looking at the tyre difference, is that at high speed, the narrow tyre will clear a lot less water, hence the tread effectively becomes waterlogged & then aquaplanes. The wider the tyre the more water it can shift at the same speed, so it doesnt aquaplane.

My 185/60 winter tyres are brilliant in the rain, i can go at mental speeds & they feel totally planted, pass bmw's etc....infact one chap tried keeping up, & soon backed off (i wonder if his steering suddenly started to go light).

Aquaplaning is quite an odd sensation, the steering seems to go light & then you notice you arent going in a straight line anymore, but thats what happens when you run michelins with low tread levels

I guess if people have had experiences of the type mentioned, then perhaps the science behind this is either very strange or misunderstood. I'm not saying i'm right & that others are wrong, but it does seem strange that you can have such polar opposite opinions/experiences on the subject.

When i got the tzd, i was running the obligatory 165/70's & in the rain they were utter shite, not so much aquaplaning, as i didnt feel confident in going that fast because even with abs, the car just wouldnt slow down. Soon as i stuck on 185/60's, everything seemed to improve by a considerable amount.

Interesting topic this, anyone had similar or totally opposite experiences?

[mat_fenwick]

This is obviously non scientific and completely subjective, but here is what I have found. With my BX I have have done about 10k miles on 165s, followed by about 50k miles with the same brand of 195s (with a couple of hundred scary miles inbetween on Hankook 195s)
I never had any problems with aquaplaning on the 165s, and only on the 195s when they get low on tread, which is to be expected. Neither tyre breaks away suddenly, but I feel safer with the 195s as I can corner significantly faster (in the wet and dry) before they start to break away... The downside is obviously with any grippier tyre, the speed you are travelling at when they do lose grip will be higher, giving you less time to react.

[BX Bandit]

Likelihood of aquaplaning is a measure of the tyres ability (or inability) to disperse water quickly enough to keep the tyre on contact with the road. The narrower the tyre, the greater the specific force (or pressure) is exerted against that of the resistance of the water to move out of the way quickly enough. So, the narrower the tyre, the greater the pressure and so the least resistance to lifting/aquaplaning.

It's the same principle as..."Would you rather have an elephant or a woman in a stilletto stand on your foot" !

[mat_fenwick]

The wider the tyre the more water it can shift at the same speed, so it doesnt aquaplane.

This is true, but also the more water it has to shift in order for it to make complete contact with the ground...also the less pressure (basically force/weight divided by contact area) you will exert on the water to move it out of the way.

Very interesting topic this!

*Edit - looks like I have repeated what others have already mentioned...

[MULLEY]

So who's right then

[jonathan_dyane]

So who's right then

Check out page 170 of this. A rather informative piece on wide vs narrow...

[MULLEY]

Interesting article, but it didnt really provide any scientific testing comparison data, so i remain unconvinced that skinny is better.

Perhaps the aquaplaning principle does corrorborate the theory that skinny tyres are less likely to aquaplane, however, by the very nature of the fact that they are narrow, they have less mechanical grip, so potentially safer at speed regarding aquaplaning, but thereafter totally hopeless at going round corners & trying to stop the car in a straight line.....

Anyone one else subscribe to my thoughts?

[mat_fenwick]

I think so, my understanding and experience is that (aquaplaning aside) you will get more grip from a wider lower profile tyre.

But, the speed at which you will have to travel to avoid aquaplaning will be lower with a wider tyre than a narrow one.
Now, depending on the tread depth, pattern and amount of water on the road, and the difference in tyre widths that speed difference may be fairly irrelevant. I.e. you will aquaplane at 80mph instead of 100mph. BUT, there is also the potential for that speed difference to be important - say if you hit a couple of inches of water it might be 20 mph versus 40mph.

Food for thought but I guess you can't simply say that wide/narrow is 'better'.

[Way2go]

Interesting article, but it didnt really provide any scientific testing comparison data, so i remain unconvinced that skinny is better.

The data fact is that the footprint area is the same except that what is added to the 'wide' is taken away from the extra 'front to back' you get on the skinny.

Perhaps the aquaplaning principle does corrorborate the theory that skinny tyres are less likely to aquaplane, however, by the very nature of the fact that they are narrow, they have less mechanical grip

Not true about having less mechanical grip, compound for compound but there will be pluses and minuses for each depending upon the direction of forces applied to the car.

skinny tyres are .............. totally hopeless at going round corners & trying to stop the car in a straight line.....

Wider tyres may be better for faster cornering because they are less prone to lateral distortion of the footprint but given that you have the same area footprint, stopping is not really affected. If any wheel locks and skids, road resistance will be reduced and that is where the purpose of ABS comes in (if you have it) to momenarily release that brake and reapply it at it's maximum efficiency through the tyre to regain braking force and stability.