Whats a reasonable mileage?

[Hutch]

It's all about the foorprint profile or the tyre, the Prof has given a fantastic, tech write up. But the Footprint profile as to how well a specific tyre will get rid of water to give a better grip. The Cheaper tyres may have a different compound and depending on how (hard , rough,) You drive your car, depends on what you request from your tyres. Fast into corners brake hard in the rain, as opposed to gentle driving, its all up to your own preferences, Winter tyres, I love them but dont buy them as if the weather is that bad, walk to the pub with the dogs. Rather than drive them to the woods.

 

[ProfJohnL]

If you walk you can always have a few more drinks anyway

 

[Hutch]

Over Say , 2 years and 30 k miles, I would rather spend £500 on tyres and feel really safe than save £200 and feel a bit iffy in the rain. . My main concern are my family and myself and an expensive car. .Saftey First for me.

 

[Parksy]

Edited text by PJL

Jonny,

You are correct that all these other factors you mention will have an effect on tyre wear, and I don't discount them, but Dusty had a question about my initial comment, specifically questioning the basis that circumference affects tyre wear, That required me to answer his question with the detail I provided. I perhaps should have stressed more strongly that this is just one aspect of many that affects tyre wear but I did make that point in my initial comment.

It is tiresome in the extreme to be continually told by the same FEW contributors that my answers are unwelcome.

This is an open forum where anybody can read the threads. Whilst an OP may have a specific problem that needs to be addressed, there may be several other readers with similar issues, and who appreciate the background and detail rather than just " fix it this way" answers.

I will point to the fact that I have received many thank you's for the answers I give. and that I believe justifies my methods.

All forum contributions which are relevant to any aspect of leisure touring caravan ownership are welcome on this forum.
Some forum users might agree with a given point, others might disagree but it's for each individual to decide for themselves if they want to read or to act upon the technical advice that's offered.
My own advice to all forum users is quite simple and straightforward, if technical information is not your thing it's easy to skip the replies containing this technical information, there are plenty of varied comments on this forum and website, so simply move on to the next thread.

 

[Dustydog]

Thanks for all that Prof.
I fully understand your point regarding angle of attack. Please will you clarify one more thing for me?
We all agree from a safety point of view the bigger the actual contact foot print the better the road holding will be . Well I think so??
We agree tyre pressures will change both footprint and angle of attack.
In truth is the difference in foot print size from small to large diameter tyres that different?

 

[KeefySher]

Thanks for all that Prof.
I fully understand your point regarding angle of attack. Please will you clarify one more thing for me?
We all agree from a safety point of view the bigger the actual contact foot print the better the road holding will be . Well I think so??
We agree tyre pressures will change both footprint and angle of attack.
In truth is the difference in foot print size from small to large diameter tyres that different?

Not necessarily. wider tyres with less tread are not so good in the wet nor snow. No tread on very wide tyres are excellent at mega speeds i.e. F1, but not legal on the road, and tyre wear is incredible. Tyres are a compromise of so many variables, not just limited to technical, but commercial and aesthetic considerations, to give singular definitive answers tbh.

 

[Raywood]

Thanks for all that Prof.
I fully understand your point regarding angle of attack. Please will you clarify one more thing for me?
We all agree from a safety point of view the bigger the actual contact foot print the better the road holding will be . Well I think so??
We agree tyre pressures will change both footprint and angle of attack.
In truth is the difference in foot print size from small to large diameter tyres that different?

The width of the tyre will certainly affect the footprint but I would think the diameter has less effect but the tyre pressure might.

 

[JonnyG]

Edited text by PJL

Jonny,

You are correct that all these other factors you mention will have an effect on tyre wear, and I don't discount them, but Dusty had a question about my initial comment, specifically questioning the basis that circumference affects tyre wear, That required me to answer his question with the detail I provided. I perhaps should have stressed more strongly that this is just one aspect of many that affects tyre wear but I did make that point in my initial comment.

It is tiresome in the extreme to be continually told by the same FEW contributors that my answers are unwelcome.

This is an open forum where anybody can read the threads. Whilst an OP may have a specific problem that needs to be addressed, there may be several other readers with similar issues, and who appreciate the background and detail rather than just " fix it this way" answers.

I will point to the fact that I have received many thank you's for the answers I give. and that I believe justifies my methods.

hi prof... Firstly i never said your answers were unwelcome on the contrary numerous occasions i have stated the opposite! please do not attribute things i have not said, to me! and please do not cloud the issue either . i stated TWICE i believe circumference is not a factor in tyre wear not in so far as car or caravan tyres are concerned i have also stated why i believe this to be so . i will go further and state i also believe the attack angle also plays no part in tyre wear in so far as either of these 2 things contribute together less than 1% to the actual wear of a tyre [which is what is being discussed right] . history notes that popularity of an answer does not actually make it correct ... the link is to the Adac test who test all tyres for all the important stuff... contrary to Popular belief some Pirelli' tyres have an excellent wear rate and come near the top of the list..

http://www.tyrereviews.co.uk/Article/2015-European-Tyre-Test-205-55-R16.htm

 

[emmerson]

Over Say , 2 years and 30 k miles, I would rather spend £500 on tyres and feel really safe than save £200 and feel a bit iffy in the rain. . My main concern are my family and myself and an expensive car. .Saftey First for me.

EH, may I say that I have never heard of budget tyres being blamed for any accidents!
If I drove a high performance sports car then probably yes, I would buy tyres to suit that car, but as I don't, and I am not a high performance driver, I fail to see the point in paying more than necessary for my roadwear. Also, I have never noticed my tyres feeling "iffy" in the rain, nor do I feel that I am compromising on safety. I've driven Range Rovers for over twenty years always on non-expensive rubber, and never had any problems so will continue to do so.
As I said earlier, pay your money, make your choice.

 

[ProfJohnL]

Thanks for all that Prof.
I fully understand your point regarding angle of attack. Please will you clarify one more thing for me?
We all agree from a safety point of view the bigger the actual contact foot print the better the road holding will be . Well I think so??
We agree tyre pressures will change both footprint and angle of attack.
In truth is the difference in foot print size from small to large diameter tyres that different?

Hello Dusty.
I'll respond to your points in reverse order.
Footprint area; Pressure is by definition force per unit area, hence being described as lbs per square inch, or Newtons per square meter or as a unified units Pascals or Bar.

For any given load on a pneumatic tyre the contact area with the road will be fundamentally determined by the pressure inside the tyre. There are some other small factors such as caracas strength, but these are small in relation to real world tyre loads and pressures. So broadly Load divided by Pressure = contact area.

This applies regardless of the diameter or circumference of the wheel.

If you are comparing two tyres of different diameters but importantly retaining the same width and load, then the length of the contact area (the chord) will be the same. But the attack angle will be different as the inclusive angle of radii from the transition points to the axle will be smaller on the larger diameter wheel.

In the main wider tyres do tend to offer more grip, but there are limits as to how far this concept can be stretched. Consider the vehicles designed to traverse soft snow. They have big tyres or tracks so the pressure (Load per unit area) they exert on the soft snow doesn't cause the snow to deform much. The same is true of tyre rubber but in this case you need enough pressure to cause the rubber to deform and conform around the irregularities of the road surface to produce a mechanical lock. If you increase the surface area too far and thus reduce the pressure, the tyre won't conform and will slip across the tops of the road irregularities.

 

[Hutch]

Prof, whilst you are almost totaly accurate as always, the new Winter "snow tyres" on cars are designed to Grip snow, ie the rolling up the snow man effect, they grip the snow via the little snipes , to grip more more snow, to get traction, but when the conditions are slushy that when the gullys and ribs work as in icy conditions, the agricultural and go every where truck have the big V treads. Without the snipes and dig into the snow.

 

[ProfJohnL]

Jonny

I will state again my answer was to a specific point Dusty was unsure about. Admittedly its perhaps more academic than practical, but I made no claims about the degree of wear, only that is it was a factor that I had considered. But even if the effect is as low as the 1% difference you suggest, it is still a difference even if its is swamped by other factors.

If you can't accept the logic of the attack angle argument, then assuming the same load is carried and other external conditions are the same there is still the inevitable difference that a larger diameter tyre has a greater circumference. This means for a given distance travelled the wheel will make fewer revolutions and thus must be able to travel further by the ratio of relative circumferences which simplifies becasue Circumference is Diameter x Pi simplifies to relative diameters. For example a 20" wheel has 11% more circumference compared to an 18" wheel.

The link you gave has no relevance to the point I was making, which was the comparison of diameters/circumferences and not claims by manufacturers of eco credentials or brand comparisons.

 

[ProfJohnL]

Prof, whilst you are almost totaly accurate as always, the new Winter "snow tyres" on cars are designed to Grip snow, ie the rolling up the snow man effect, they grip the snow via the little snipes , to grip more more snow, to get traction, but when the conditions are slushy that when the gullys and ribs work as in icy conditions, the agricultural and go every where truck have the big V treads. Without the snipes and dig into the snow.

Yes Hutch quite true but I was specifically referring to vehicles "traversing soft snow" where collapsing the snow would be detrimental to progress like in deep arctic snow fields etc.

 

[otherclive]

Thanks for all that Prof.
I fully understand your point regarding angle of attack. Please will you clarify one more thing for me?
We all agree from a safety point of view the bigger the actual contact foot print the better the road holding will be . Well I think so??
We agree tyre pressures will change both footprint and angle of attack.
In truth is the difference in foot print size from small to large diameter tyres that different?

Hello Dusty.
I'll respond to your points in reverse order.
Footprint area; Pressure is by definition force per unit area, hence being described as lbs per square inch, or Newtons per square meter or as a unified units Pascals or Bar.

For any given load on a pneumatic tyre the contact area with the road will be fundamentally determined by the pressure inside the tyre. There are some other small factors such as caracas strength, but these are small in relation to real world tyre loads and pressures. So broadly Load divided by Pressure = contact area.

This applies regardless of the diameter or circumference of the wheel.

If you are comparing two tyres of different diameters but importantly retaining the same width and load, then the length of the contact area (the chord) will be the same. But the attack angle will be different as the inclusive angle of radii from the transition points to the axle will be smaller on the larger diameter wheel.

In the main wider tyres do tend to offer more grip, but there are limits as to how far this concept can be stretched. Consider the vehicles designed to traverse soft snow. They have big tyres or tracks so the pressure (Load per unit area) they exert on the soft snow doesn't cause the snow to deform much. The same is true of tyre rubber but in this case you need enough pressure to cause the rubber to deform and conform around the irregularities of the road surface to produce a mechanical lock. If you increase the surface area too far and thus reduce the pressure, the tyre won't conform and will slip across the tops of the road irregularities.

Just as a slight aside when I worked in Canada very few seemed to drive on winter tyres as they were unheard of for city folks. Within Ontario you could only fit chains when you were not driving on tarmac roads. At the time I had Jeep CJ7 Renegade 4.2 litre straight six 98bhp soft top, which I had bought from a chap in Hawaii. It came with wide sand tyres; so pleased as punch with my purchase I took it out for a drive not long after it had snowed, and the roads had been ploughed and the ordinary cars seemed to be doing okay. But after performing a couple of unplanned doughnuts I suspected that my wide, mainly slick, surfer's rubber wasn't going to hack it in Canada. So I swopped the tyres for something narrower and with some tread patterns not unlike those which I had on my Marina which languished back in UK. After that the Jeep was a good drive, well as good as a Jeep can be.

 

[JonnyG]

Jonny

I will state again my answer was to a specific point Dusty was unsure about. Admittedly its perhaps more academic than practical, but I made no claims about the degree of wear, only that is it was a factor that I had considered. But even if the effect is as low as the 1% difference you suggest, it is still a difference even if its is swamped by other factors.

If you can't accept the logic of the attack angle argument, then assuming the same load is carried and other external conditions are the same there is still the inevitable difference that a larger diameter tyre has a greater circumference. This means for a given distance travelled the wheel will make fewer revolutions and thus must be able to travel further by the ratio of relative circumferences which simplifies becasue Circumference is Diameter x Pi simplifies to relative diameters. For example a 20" wheel has 11% more circumference compared to an 18" wheel.

The link you gave has no relevance to the point I was making, which was the comparison of diameters/circumferences and not claims by manufacturers of eco credentials or brand comparisons.

hi prof i never claimed to doubt the physics involved in your answer ie attack angle, but and please take this the right way. your 18inch compared to a 20 inch wheel is irrelevant in my mind .please let me explain why. ....I take this from a car tyre perspective .. my car comes with 16 17 18 and i believe 19 inch wheels .if somebody wasn't totally up on this subject and by that i mean people who read and take it at face value, they could quite easily think that having a bigger wheel would give them a larger circumference and therefore the so called benefits you are claiming ..but that is simply not true a 16 or 17 inch whee with/tyrel could give a larger circumference wheel/tyre than an 18 or 19 inch does. its the tyre size more than the wheel that effects the circumference . and my eirlier post should have explained this poorly i admit. .that even though a car manufacturer can have several wheel size choices for a given car once the recommended and appropriate Tyre size is fitted the end circumference near as dam it will be the same regardless of whether its a 16 inch or 19 inch wheel .so there is no point in somebody looking to fit a larger wheel to maybe try and benefit from any so called benefit they could get due to a larger circumference wheel. of course for me if indeed there was a benefit from any of this i still feel the potential extra tyre and wheel weight would counter it...

 

[ProfJohnL]

Jonny,

A car wheel consists of a rim and tyre, therefore my comment is correct . You have assumed my referenced to particular wheel diameters are rim sizes. If that had been the case then you would have been correct.

 

[Hutch]

Well George, you have had ..great response to a gentle post, I am changing my Hankooks for Nokien Weatherproofs. See how they run.

Give me a bell sometime, if younfancy a beer, , just decorating.
Very best regards.
Hutch.

 

[Gafferbill]

Given that tyre pressure and tracking for a given tyre is correct then by far the biggest factors determining tyre wear are.........

Driving style of the driver and the proportion of mileage driven on motorway standard roads.
I personally prefer to move fronts to back to balance out tyre wear over the life of all 4 tyres.

 

[otherclive]

Well George, you have had ..great response to a gentle post, I am changing my Hankooks for Nokien Weatherproofs. See how they run.

Give me a bell sometime, if younfancy a beer, , just decorating.
Very best regards.
Hutch.

My son' who could be called "a spirited driver" has Nokian Weatherproofs on his Freelander 2 and rates them highly. No idea how they are wearing but he's been in snow, mud and wet grass and was very satisfied with them and they are a quiet tyre on tarmac.
My Forester's OEM Yokohama G91F V-rated have 23000 miles and are down to 4mm. So as I normally change at 3mm they will be changed in early summer. I too will be fitting the Nokians and even though they are H rated they are suitable for the car.

 

[BedfordGeorge]

I have been busy and not on line, so surprised by all the replies, some very technical, my thanks to everyone.

The one item I did not confirm was the tyre information, which is as follows....225/55V17 Pirelli P7 AS Z XL

I will certainly ask about the hardness/softness of the Pirelli's but can anyone explain what the individual references for the tyre mean? ie P7 etc.

Hutch my telephone is 01234 772181 if you can call me we can arrange a meeting.

 

[KeefySher]

I have been busy and not on line, so surprised by all the replies, some very technical, my thanks to everyone.

The one item I did not confirm was the tyre information, which is as follows....225/55V17 Pirelli P7 AS Z XL

I will certainly ask about the hardness/softness of the Pirelli's but can anyone explain what the individual references for the tyre mean? ie P7 etc.

Hutch my telephone is 01234 772181 if you can call me we can arrange a meeting.

George double check as it should be 225/55R17
225 is the tread width in mm. 55 is the sidewall ratio so 55% of 225 or 123.75mm. R is the construction i.e. Radial ply. V is the speed rating. The P7 is pirellis 'model' of tyre. AS is asymmetrical tread patter i.e. can only be fitted in one direction, the direction of forward travel. Z is the speed limit. XL is extra load rating.

 

[BedfordGeorge]

Hi Keefy,
The information I gave was from my invoice, however I checked for the original replacement tyres, which were Kumho 235/ 55 WR17. I have just checked the actual tyres fitted and they are 235 / 55 R 17 so the 225 is a typo at the garage. Thanks for the other explanations on the lettering.
I have just checked the original KIA Specification Leaflet and it shows 225 for my TITAN model, so I will telephone KIA in Milton Keynes to check what is correct, as it may be the reason for my low mileage. I also checked my original replacement tyres (2) and they were done at 19,000 with the following (2) at 26,500, but cannot remember which were replaced first front or rear.
Again thanks to all for your comments and information.