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Pros: Wider rubber = more contact = more grip, all things being equal, but see below.
Look better?
Cons: Stiffer sidewalls and higher air pressures = less deformation on the road surface which acts against grip.
Wider tyre could mean a greater likelihood of aquaplaning, and will be worse in snow for similar reasons.
Other points to note are the often (much) higher replacement costs, and the lifetime may be shorter, dependent on the suspension geometry perhaps. Ride quality also frequently suffers.
Worth noting HJ has has pointed out in his column in the past, if memory serves, that tyre manufacturers apparently provide loss-leading low profile tyres to car manufacturers in the knowledge that if they can get them on the vehicle when sold new, they'll likely coin it in when replacements are due. If a car manufacturer has the opportunity sell a fashionable upgrade (bigger wheels/tyres) on that basis then they are hardly going to turn it down.
Look at the wheels/tyres on F1 cars for guidance on whether it is as straightforward as lower profile = better.
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Point of comparison, how much does an F1 car weigh?
edit, in my previous ost i mention 195/65 x 16, should have read 195/65 x 15.
Edited by gordonbennet on 26/11/2014 at 11:17
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F1 Position
www.jamesallenonf1.com/2014/07/guest-blog-mark-gil.../
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Interesting, thanks for that.
There are parallels with road cars- remove the cushioning that higher profile tyres provide and in the absence of suspension adjustment the ride characteristics will change, often not for the better. F1 cars obviously have fairly unique demands on the suspension as a light car turns into a light car with an enormous amount of downforce at speed, so the comparison is only valid up to a point.
Bottom line is, in my view- choosing the smallest wheel size which is recommended for your car does not imply a poorer performance than opting for any larger sizes allowable.
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So the only apparent reason for a change is F1 is because of "the increasingly less relevant small wheel"...
good grief...
So there's apparently no crucial performance benefit for a vehicle representing the pinnacle of speed and grip - ultimately they can make anything work, as long as all the suspension (and aerodynamics) have been engineered to match.
Even then there seems to be a questionmark that a low-profile tyre can be made sufficiently structurally sound !
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They put bigger tyres than that on a Vauxhall Corsa 1.2 these days.
Another example of out-of-hand -ness.
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They put bigger tyres than that on a Vauxhall Corsa 1.2 these days.
Another example of out-of-hand -ness.
Yesterday I saw a Vauxhall Adam with ridiculously big wheels on it. Had a look at their car configurator this morning, found that they are 'proper' Vauxhall ones - they are 18".
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VX have form for the ridiculous, seen some Diesel Insignias with 20" wheels on, IIRC 30 aspect spray on tyres.
Hated delivering those or Jags with similar sizes, if you touched anything on the transporter decks the wheel was ruined, and too easy by far to wheelspin when reversing a Jag up a wet deck with about an inch room either side of the wheels through the narrows.
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Take my Caterham as an example.
My current car was built back in 1992 and at the time it was becoming popular to fit 15" wheels to them instead of the 13" ones I had on my first Caterham. I went with the consensus because I was using the car in hillclimbs and sprints at the time and it was becoming difficult to get 13" tyres in the soft compound required. With the 15" wheels fitted (195 50 15 tyres) it gripped very well but the handling was not predictable. It would break away with no warning and catching the slide was very difficult. I and others tried different spring rates, anti roll bars and played with tyre pressures but the result was always the same.
A few months later a small American tyre manufacturer started importing tyres into the UK that were used in the states for what the called "autocross", basically races in car parks. Very soft compound and available in the 185 60 13 size I had used previously. Bought a set and compared to the 15's they looked very narrow, other competitors were clearly unimpressed. But size was clearly very important (as was the compound) and after a couple of events I was setting new records. The car was a pleasure to drive, very forgiving but in truth not as much ultimate grip. But you could use all the grip and beyond because the car let go predictably and allowed you to correct it with no drama.
For the next 9 years of competing I used the 13" wheels with various tyres with decent results all the time. But by 2003 decent 13" tyres approved for the class were dead and gone so it was 15" or nothing. So I went back to 15" wheels and after 4 events gave up for good, no fun at all. Since then good 13" tyres have come and gone, no idea what the current favourite is.
I only use the car on the road now so ultimate grip is not a priority but for the best overall compromise I use a 185 60 14 tyre in a softish compound with a tread pattern that is good in our wet summers. The extra rubber in the sidewall helps with the ride and the lighter weight also helps.
Some complete muppets use 18" or larger wheels on similar cars with rubber band tyres purely for the looks. God knows how they keep them on the road.
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>>>"a 185 60 14 tyre in a softish compound with a tread pattern that is good in our wet summers."
What make/model of tyre are those, if I might ask just out of curiosity, Skidpan?
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I believe the possible move to larger wheels for F1 is due to the wish to standardise wheel and tyre sizes accross a number of racing series (F1, GP2, WSC etc. This is to help to cut costs.
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What make/model of tyre are those, if I might ask just out of curiosity, Skidpan?
Its a Yokohama A021R. Its been a control tyre in various race series for many years (early 90's) thus is has been available at reasonable prices. Get about 10,000 miles out of a set, for me that is 5 years on the road. Its DOT and E marked thus fully road legal.
But now there is a problem. As of November 01 this year all new tyres must be energy rating "F" or below to be sold as road legal. The Yokohama 021 has not even been tested thus it is no longer legal to import them for road use, new imports will not be E marked. Old stock E marked tyres can still be sold for road use (plenty of stock in the UK) and tyres already on cars are still legal to use on the road so I am OK for another couple of years at least.
During that time lets hope that Yokohame bring out a new tyre or get the 021 approved. They already have a tyre called the Neova AD08R which is a soft compound E marked "track day" tyre with F rating for energy thus legal to keep selling but its only available in 15" and above, don't want to go there again.
Nankang have a fully legal soft compound trackday tyre in 14" sizes but not sure about using a posh ditchfinder until someone else tests them.
Edited by skidpan on 26/11/2014 at 13:57
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When you say "all new tyres must be energy rating F or better", do retread tyres not count as 'new', then?
because I see Mytyres and Tyreleader (for example) are still listing retread tyres for sale, and they don't ever seem to have values listed for their energy rating, wet grip, noise.
I'd bet that if Nankang have got their soft compound correct, the tyres will be acceptable enough - they've been around for quite a while now, compared to some of the more dubious Chinese makes whose brand-name and factories were only born in about 2009.
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When you say "all new tyres must be energy rating F or better", do retread tyres not count as 'new', then?
No idea about retreads specifically but if the tyres were made before 01 November 2014 it is still legal to sell them regardless. What happens with new production I know not.
Edited by skidpan on 26/11/2014 at 14:20
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Many thanks for the extensive response to my original query. On balance it sounds as though for the majority of 'ordinary' family motorists the low profiles are a waste of money (I assume that they are more expensive than their higher profile brothers).
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Yes, they are usually more expensive. As has been said, they might, possibly, maybe, give you a fraction more grip on a road, if cornering at the limit of the car's ability. Or they might not. They are generally fitted for style rather than anything else.
A few years ago I bought a BMW 320i estate (my first BMW estate, actually). It handled like an absolute pig, was horribly twitchy, with a bumpy, unforgiving, uncomfortable ride, due to the 18" M-sport alloys that someone had fitted to it, compared to the 16" wheels that it originally came on.
I managed to find a set of BMW 16" wheels on the evilbay, bought them, got a set of brand new Pirellis fitted to them, and then managed to sell the 18" wheels for considerably more than my outlay on the 16"s and tyres. It made an incredible difference. Instantly, the car held the road better, you didn't have to make constant steering corrections, it was massively more comfortable.
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There is an increase in the likelihood of aquaplaning on a tyre with a low profile. In broad terms aquaplaining can occur at a speed of 9 times the square root of the tyre pressure, and lthough with some modern tyres this can be 7 or 8 times ie a little lower
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There is an increase in the likelihood of aquaplaning on a tyre with a low profile.
Don't think you can really say that as a general comment, there are many factors.
Surely a low profile tyre with a full tread would be better than a warn higher profile tyre.
Some tyres have a higher resistance to aquaplaning than others because of the tread design.
The width of a tyre also has a major effect. Wider tyre will generally be more prone to aquaplaning than a narrower tyre and since most very low profile tyres fitted are also very wide I suspect there is more than the profile at work.
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Interesting.
I wonder if there's an ideal common sense size thats right for each vehicle, mainly based on weight versus power.
Rob's 3 series could maybe have been too light for an 18" wheel, 16" perfect size?
Probably a similar weight and power to my Merc W124 coupe, that felt 'undertyred' on the stock 15", and maybe i went an inch too big with the 17", as i said before had there been some better wheel options then i would have gone for a 16" fitted with that ideal mid car size 205/55 x16.
Taking that as a theoretical medium weight fairly powerful car ideal tyre size, we could sensibly suggest that 17" elastic bands on a Corsa would be not only ludicrous but make the car dangerously jittery, similarly that 16" perfecto would be struggling the other way fitted to a Lexus 600.
Makers don't always get things right, we bought a new Hilux Invincible in 2007, that came on a unique size to the spec of 255/65 x 16, it took but a few weeks of driving to feel that size simply wasn't right for the vehicle in any way, again i use the term 'undersized', prone to ploughing on and then flip to oversteer, not nice at all and not helped at all by the Invincible having a very (maybe too) effective rear LSD as standard.
Had already made enquiries i didn't pursue about privately importing a Taiwan (hang on, Thailand) built Hilux of similar spec (V6 petrol engine for LPG conversion) so knew that on those vehicles the tyre size (identical dimension wheels) was 265/70 x 16, so bought a set of those and sold the OE Pirellis on...i should add at this point European Hilux's were made in South Africa.
Well, what a revelation the vehicle was transformed, with the solid stable predictable handling it should have had from day one, and as a bonus the speedo now showing 71mph @ 70...and no coincidence maybe that the main UK dealer demo (we enquired about buying) had already been written off when a salesman had spun out on a roundabout.
Fast forward 12 months and the Hilux Elk Test Fail video turned up on youtube (feel free to look it up), within weeks Toyota had one of their regular knee jerk reactions and recalled Invincibles fitted with 16" to be refitted with the 15" tyre/wheel combo from the other spec models, this instead of simply looking at the sizing of the rest of the world, eureka!, new Invincibles from then would come on the new size....now superceeded again with the facelift going up to 17" but now with traction control etc.
The 15" retrofitted tyres when put through the calculator ended up exactly the same overall size as the larger 16" tyres that rest of world fitted, quite how Toyota missed the blindingly obvious there i don't know.
Refused the recall as quite happy with what should have been the correct size from day one, indeed many other owners of same spec did the same.
Edited by gordonbennet on 27/11/2014 at 09:20
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Vauxhall seem to have gone from one extreme to the other,
I remember a friend buying a Vauxhall Nova TD around 1990 and it came with steel wheels and 145r13s as standard. (I can't remember if they were 70 or 80 profile now.
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145s would have been alright for that Nova. That was the width on my dad’s Renault 16 and Peugeot 305. I also noted not so long ago that a Peugeot 405 estate had only 175 width tyres.
I wonder why French cars typically used to use relatively narrow tyres?
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>>aquaplaining can occur at a speed of 9 times the square root of the tyre pressure
Careful, this is often misconstrued as the air pressure inside the tyre and not the pressure between the tyre and the road surface.
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Careful again though: Within upper and lower limits, the air pressure inside the tyre does affect the pressure between the tyre and the road surface:
At a low internal pressure, more of the circumference of the tyre will deform and end up flat on the road surface, so the contact area increases.
At high internal pressure, the tyre deforms less than normal and becomes more like a solid rim, so the contact area decreases.
The weight of the car is the same, so the pressure between the rubber and the road surface reduces in the first case and increases in the second case.
It's then a tradeoff: High internal pressure makes higher external pressure so reduces the risk of aquaplaning, but you have decreased the size of the contact patch that the manufacturer is supposed to have carefully determined is optimal, so presumably you will have less actual grip.
On a side issue: How do these now-compulsory Tyre Pressure Monitoring systems behave if you deliberately choose to run your tyres somewhat above (or below) the standard pressure?
Or do they only create a fuss if the pressure gets blatantly low?
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On a side issue: How do these now-compulsory Tyre Pressure Monitoring systems behave if you deliberately choose to run your tyres somewhat above (or below) the standard pressure?
Or do they only create a fuss if the pressure gets blatantly low?
There are 2 types of system.
The first is a simple one based on the speed of rotation of a wheel based on the ABS sensors. When a tyre goes soft it rotates faster and when the pressure drops by about 30% compared to the others it throws up a warning. Easy to calibrate, press button on dash or in the computer and drive for a few minutes sorts it. Nothing to go wrong, no fancy parts but it does not show which tyre has the problem. But you still need a pressure gauge. To finter winter wheels nothing to do other than press the recalibrate button. In theory if all 4 tyres were at 1/2 pressure and the button had been pressed it would think all was normal.
The second is the type that uses special valves. These display the actual pressure on the dash display. They have to be calibrated by the dealer or others with the right kit. The valves can be as much as £150 each and are easlliy damaged by a gorilla of a tyre fitter plus they can corrode and break. To fit winter tyres you need 4 additional valves fitting and calibrating if you have 2 sets of wheels. The wheels need to be compatible with the valves. Advatage is a total muppet never needs to check the pressures (providing its working correctly).
Even though it has drawbacks I stiil prefer the first type of system.
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On a side issue: How do these now-compulsory Tyre Pressure Monitoring systems behave if you deliberately choose to run your tyres somewhat above (or below) the standard pressure?
Or do they only create a fuss if the pressure gets blatantly low?
A lot of the systems work by measuring the rate that the roadwheels are turning at - if a particular roadwheel suddenly starts rotating 3 or 4 % faster due to a deflated tyre, then it determines that you've got a puncture.
In general, when you get a new tyres fitted, or if you check your pressures and notice they are a little low and add some air to the tyres, you might get a warning bong and light within a few miles. As such, it is recommended that you re-initialise the system, so it looks for differences from the 'new' rolling rate.
There are systems that work by pressure sensors too. I have no idea how those work, especially if you load up the car and add air pressure to the back wheels, for example, as so many cars seem to recommend.
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Good heavens - no wonder whoever it was had a short list of potential new cars due to trying to avoid tyre pressure monitoring!
But if it's now compulsory, presumably the rotation speed system is the preferable option.
£150 for a valve?!? Will everybody have to pay £10 to the tyre fitters for an insurance premium in case they wreck them, in addition to the 'disposal fee' that got introduced in the past...
Yet another answer to a question nobody really asked.
In my experience, a tyre has to become pretty darn seriously underinflated to become truly dangerous: I've driven with about 8 PSI in a rear tyre and noticed the car 'getting a bit sloppy': Normally I will have noticed, or someone else will have pointed out to me, that a tyre is obviously rather flat-ish long before it gets that low.
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Good heavens - no wonder whoever it was had a short list of potential new cars due to trying to avoid tyre pressure monitoring!
That was me and there is no way I want a car with those mega expensive valves.
Have had 3 cars now with the simple system based on the ABS and its just fine. As far as I am aware only VAG and BMW use such a system currently but I suspect the more expensive cars on both makes books have the valves fitted.
Problem with running as low as 8 psi is the heat it generates. Although the tyre appears OK and most garages will repair them unseen damage can be done to the carcas which only appears at the most unfortunate time.
Even with the chepo system you get a warning that gives you plenty of time to get some air in before a disaster.
But at the end of the day some idiots will simply ignore any warning.
Edited by skidpan on 27/11/2014 at 15:48
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Good heavens - no wonder whoever it was had a short list of potential new cars due to trying to avoid tyre pressure monitoring.
I think all new cars from last month have TPMS as standard (not ABS-based flat tyre warning)
2.2 Firestone recall and legal mandates
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Good heavens - no wonder whoever it was had a short list of potential new cars due to trying to avoid tyre pressure monitoring.
I think all new cars from last month have TPMS as standard (not ABS-based flat tyre warning)
2.2 Firestone recall and legal mandates
Indirect TPMS (using ABS) is permitted according to the link you posted
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Good heavens - no wonder whoever it was had a short list of potential new cars due to trying to avoid tyre pressure monitoring.
I think all new cars from last month have TPMS as standard (not ABS-based flat tyre warning)
2.2 Firestone recall and legal mandates
Indirect TPMS (using ABS) is permitted according to the link you posted
Correct. Skoda (spoke to them yesterday) and Seat still use the ABS system but not sure if the other VAG companies (upmarket?) use a direct one now since it looks more impressive when you switch the car on.
BMW used to use the indirect ABS method on cheaper cars but I suspect that they use the direct method now, the brochures clearly show a screen with a car and individual pressures which is something ABS system could not do.
So it still looks like another Seat or Skoda if I am to aviod both direct TPMS and electronic handbrake on our next car.
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In my experience, a tyre has to become pretty darn seriously underinflated to become truly dangerous: I've driven with about 8 PSI in a rear tyre and noticed the car 'getting a bit sloppy': Normally I will have noticed, or someone else will have pointed out to me, that a tyre is obviously rather flat-ish long before it gets that low.
It does of course relate to the rate of air loss - the initial loss during a slow puncture may be un-noticed - but that same initial pressure loss for a full-on puncture could be down to grip-loss levels in seconds rather than days - so TPMS should give the driver time to slow down and pull over.
Some, but not all, blow-outs are preceeded by reduced pressure causing temperature to rise and actually causing the blow-out - these will be prevented.
But some genuinely instant blow-outs can't be avoided.
Edited by RT on 27/11/2014 at 15:57
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Now that Michelin is reportedly marketing airless tyres, soon we might be going 'no profile', never mind low profile !!
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My former brother in law has just purchased himself a brand new BMW 330d on 19" wheels. He may as well have scribbled the tyres on with a a sharpie marker. I can't imagine that it'll be comfy but he's a pilot so he's got more money than sense and a lot of free time to whizz about in it. He's only in his 20s as well, so I guess his back will not protest at speed bumps and pot holes he encounters.
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Now that Michelin is reportedly marketing airless tyres, soon we might be going 'no profile', never mind low profile !!
I expect they will sell well to to 4x4 crowd who can`t get over speed humps fast enough
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