Mixing tyres?
- Thread starter TONYMOR
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Many years ago I swapped out the tyres on my capri (tail happy cars for those of us of a certain vintage) - being a pimply oik I could only afford a couple at a time so had the new (at that time) Goodyear eagles on the back with Firestones on the front (SC211) I had the only Capri that was front happy - after that I used the same pattern of rubber all around.
As has been said those four little patches are the only thing keeping you on the road - don't skimp on them
As has been said those four little patches are the only thing keeping you on the road - don't skimp on them
this is getting heated again...
the only difference between a bridgestone runflat and a bridgestone non run flat is the sidewall. Which will be a lot stiffer on the run flat. the tread pattern, tread depth and rubber compound will all be the same.
I would argue that any of tread pattern, tread depth, rubber compound, tyre widths, tyre pressures and wheel alignment all make way more of a difference to how a car feels than the stiffness of the sidewall.
it seems bizarre to me that people happily recommend fitting different width and profile tyres to cars, which will make a huge difference to a cars balance front and rear, yet suggest mixing otherwise identical run flats and non run flat tyres is seen as a sin punishable by death, and you are the scourge of the community.
if you do mix tyres, you wont instantly die in a fireball, but if you are exploring the limits of tyre performance on the road for some reason, be aware that the stiffer sidewalled tyre will respond differently to the softer sidewalled tyre. this is the same if you mix a soft sidewall tyre (like goodyear) with a hard sidewall tyre (like bridgestone), even if they are both non run flats.
the only difference between a bridgestone runflat and a bridgestone non run flat is the sidewall. Which will be a lot stiffer on the run flat. the tread pattern, tread depth and rubber compound will all be the same.
I would argue that any of tread pattern, tread depth, rubber compound, tyre widths, tyre pressures and wheel alignment all make way more of a difference to how a car feels than the stiffness of the sidewall.
it seems bizarre to me that people happily recommend fitting different width and profile tyres to cars, which will make a huge difference to a cars balance front and rear, yet suggest mixing otherwise identical run flats and non run flat tyres is seen as a sin punishable by death, and you are the scourge of the community.
if you do mix tyres, you wont instantly die in a fireball, but if you are exploring the limits of tyre performance on the road for some reason, be aware that the stiffer sidewalled tyre will respond differently to the softer sidewalled tyre. this is the same if you mix a soft sidewall tyre (like goodyear) with a hard sidewall tyre (like bridgestone), even if they are both non run flats.
brillomaster said:this is getting heated again...
the only difference between a bridgestone runflat and a bridgestone non run flat is the sidewall. Which will be a lot stiffer on the run flat. the tread pattern, tread depth and rubber compound will all be the same.
I would argue that any of tread pattern, tread depth, rubber compound, tyre widths, tyre pressures and wheel alignment all make way more of a difference to how a car feels than the stiffness of the sidewall.
it seems bizarre to me that people happily recommend fitting different width and profile tyres to cars, which will make a huge difference to a cars balance front and rear, yet suggest mixing otherwise identical run flats and non run flat tyres is seen as a sin punishable by death, and you are the scourge of the community.
if you do mix tyres, you wont instantly die in a fireball, but if you are exploring the limits of tyre performance on the road for some reason, be aware that the stiffer sidewalled tyre will respond differently to the softer sidewalled tyre. this is the same if you mix a soft sidewall tyre (like goodyear) with a hard sidewall tyre (like bridgestone), even if they are both non run flats.
I'm confused. You tell us the RF and NRF are nearly identical in one breath and then warn us of their different performance in the next.
I will never mix tires again after my mismatched mishap. When the fronts took a corner the rears couldn't hold the car spun around like a top.
I would suggest that anyone who wants to mix non RFT and RFT on different axles do it and make your own mind up. I have Done it on at least two occasions and I have made my own mind up and I would do it again. I will not replace a perfectly good tyre when it doesn’t need changing. I’m lucky enough not to own a car with RFT anymore so I don’t have that issue. However there are those that say that they would never do it.
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Anonymous
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"the only difference between a bridgestone runflat and a bridgestone non run flat is the sidewall. Which will be a lot stiffer on the run flat. the tread pattern, tread depth and rubber compound will all be the same"
I think this illustrates the whole point!
Tyre manufacturers state that even apparently identical tyres in identical sizes can have fundamental differences in terms of internal construction and characteristics..so for example a BMW type approved version of a tyre was different in weight, rolling radius and compound from an apparently identical version sold on the same market for DSC/all wheel drive reasons..
For an end user the tyre sizes and their associated rim widths is well understood..a set of matched type of tyres from the same manufacturer is a whole different ball game to mixing and matching different construction methods..the only reason its not illegal in this country (it is illegal in several european countries) is not enough muppets have killed themselves in this way..and hopefully the tyre fitting companies prevent the great unwashed from doing so..
Your suggesting that people should act as test pilot and explore the limits..many real test pilots have been killed exploring the limits..
The issue is that your view does not accord with many others, you see them as righteous, nanny state worrier..
As others have said I'd be much more worried about seeing you on a wet bumpy unfamiliar road when it suddenly tightens up and my wife is coming round the corner from the opposite direction..
I think this illustrates the whole point!
Tyre manufacturers state that even apparently identical tyres in identical sizes can have fundamental differences in terms of internal construction and characteristics..so for example a BMW type approved version of a tyre was different in weight, rolling radius and compound from an apparently identical version sold on the same market for DSC/all wheel drive reasons..
For an end user the tyre sizes and their associated rim widths is well understood..a set of matched type of tyres from the same manufacturer is a whole different ball game to mixing and matching different construction methods..the only reason its not illegal in this country (it is illegal in several european countries) is not enough muppets have killed themselves in this way..and hopefully the tyre fitting companies prevent the great unwashed from doing so..
Your suggesting that people should act as test pilot and explore the limits..many real test pilots have been killed exploring the limits..
The issue is that your view does not accord with many others, you see them as righteous, nanny state worrier..
As others have said I'd be much more worried about seeing you on a wet bumpy unfamiliar road when it suddenly tightens up and my wife is coming round the corner from the opposite direction..
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Anonymous
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mr wilks said:Pbondar said:
Fortunately my wife is a decent driver with 30yrs unblemished licence but must be a worry for you every time she takes the keys off the hookmaybe some refresher lessons would help :roll:
I understand the gentle jibe...as previously discussed we see things in a different light...I hope that unlike a business colleague’s wife who is still suffering from PSD following a crash where a taxi lost control on a corner and wrote her car off that a similar fate does not befall your good wife.
The taxi had 3 different makes of radial in 4 different patterns..
Pbondar said:
Thats fine. I'll be equally worried about your wife, whose shopping car hatchback is still on its original, 9 year old rear tyres, who hasnt checked her tyre tread since the last MOT 11 months ago, has never checked the alignment, and has had a slow puncture for the last 3 weeks and not noticed. Yes, of us both, i'm clearly the risky one, because my 1 year old rear tyres are run flats, whereas my brand new front tyres are not.
I'm not recommending mixing run flats with non run flats, i'm just saying, there are many other aspects of tyres that are far more critical to how a car handles than how stiff or not the sidewall is.
This forum frequently recommends switching from a staggered tyre set up (225/255, which promotes nice safe understeer) to a square setup, for better turn in and more neutrality. But this will make a far greater difference to the average driver in the wet roundabout/tightening corner on a country road scenario. But for some reason, none of the threads recommending that as a course of action have the level of scorn and spite in them than the 'mixing runflats and non run flats' debate.
Pbondar said:mr wilks said:Pbondar said:
Fortunately my wife is a decent driver with 30yrs unblemished licence but must be a worry for you every time she takes the keys off the hook
I understand the gentle jibe...as previously discussed we see things in a different light...I hope that unlike a business colleague’s wife who is still suffering from PSD following a crash where a taxi lost control on a corner and wrote her car off that a similar fate does not befall your good wife.
The taxi had 3 different makes of radial in 4 different patterns..
No idea about the details but id be amazed if the accident didn't involve speeding over the recommended for the road where the crash happened & that's a big part of the argument.
Was it the tyres or was it the speed?
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Anonymous
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Brillomaster..no matter how much you twist n turn you’re going to lose this one.. 
My wife’s Cooper SD Mini is currently sporting its set of summer wheels with Dunlop SportsMaxx in OEM sizes on factory spec alloys..the tyres are 2 years old....for winter she runs OE alloys with Continental TS850P winter tyres in OE sizes..widely regarded as some of the very best winter tyres for Scottish type winter weather conditions..
Tyre tread was measured when they were refitted 4 months ago...since then she’s done about 375 miles so not particularly worried there..
Alignment is checked twice a year when summer and winter wheels are rotated..
Her second generation TPMS is designed to capture amongst other things slow leaks..
So you are correct you are in fact non compliant and more of a danger to yourself and society..
As you will see from a wheel database https://www.wheel-size.com/
You will see that BMW recommends both square and asymmetric setups in 17/18/19 sizes in various widths..
So square and asymmetric setups on E89s are approved / fitted by the manufacturer.
If you’re interested there are some very informative YouTube videos testing BMW cars in various square / Asymmetric configurations that do not support your postulation..
Clearly there are many factors that will compromise the integrity of the handling of the car that are tyre related..but to come back to the original point..is fitting mixed run flats and non flats recommend / approved / acceptable / illegal..
For sure the first 3 are answered in the negative..in some countries they are also illegal.. https://www.wheel-size.com/
My wife’s Cooper SD Mini is currently sporting its set of summer wheels with Dunlop SportsMaxx in OEM sizes on factory spec alloys..the tyres are 2 years old....for winter she runs OE alloys with Continental TS850P winter tyres in OE sizes..widely regarded as some of the very best winter tyres for Scottish type winter weather conditions..
Tyre tread was measured when they were refitted 4 months ago...since then she’s done about 375 miles so not particularly worried there..
Alignment is checked twice a year when summer and winter wheels are rotated..
Her second generation TPMS is designed to capture amongst other things slow leaks..
So you are correct you are in fact non compliant and more of a danger to yourself and society..
As you will see from a wheel database https://www.wheel-size.com/
You will see that BMW recommends both square and asymmetric setups in 17/18/19 sizes in various widths..
So square and asymmetric setups on E89s are approved / fitted by the manufacturer.
If you’re interested there are some very informative YouTube videos testing BMW cars in various square / Asymmetric configurations that do not support your postulation..
Clearly there are many factors that will compromise the integrity of the handling of the car that are tyre related..but to come back to the original point..is fitting mixed run flats and non flats recommend / approved / acceptable / illegal..
For sure the first 3 are answered in the negative..in some countries they are also illegal.. https://www.wheel-size.com/
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mr wilks said:Pbondar said:mr wilks said:Fortunately my wife is a decent driver with 30yrs unblemished licence but must be a worry for you every time she takes the keys off the hook
I understand the gentle jibe...as previously discussed we see things in a different light...I hope that unlike a business colleague’s wife who is still suffering from PSD following a crash where a taxi lost control on a corner and wrote her car off that a similar fate does not befall your good wife.
The taxi had 3 different makes of radial in 4 different patterns..
No idea about the details but id be amazed if the accident didn't involve speeding over the recommended for the road where the crash happened & that's a big part of the argument.
Was it the tyres or was it the speed?
I would assume that speed / surface conditions had a major factor...but why add more factors to make it more difficult for you and others?
The easiest Way to end this argument is too talk to the tyre companies direct. Ask them the question plain and simple. Take Bridgestone for instance. Email them and say I have Bridgestone run flats on all 4 corners at the moment, but I want to put 2 x non Bridgestone run flats on the front. Will this be ok?
Then ask BMW the same question.
Then ask your insurance company the same question.
I will tell you now, they will all say NO!
Why will they say no? Because it is not safe that is why. There is a lot more difference to run flats than just the side wall.
At the end of the day, you own your car, and you do whatever you want too it. A comment was made earlier in this post about if you cannot afford to run it, you shouldn’t have brought it, and that in my honest opinion is spot on.
Run flat tyres are absolutely superb, providing you have a road infrastructure that is well maintained. UK roads are shocking, and as such run flats are a poor driving experience. Drive the same car, on the same tyres in say Germany, and you will hardly notice the runflats.
If you are going to make the change, change all 4. If you cannot afford to do this, then wait until you can. If you can’t see yourself being in a position to ever change all 4 at the same time, go and buy a Honda Civic and get Tony from the back street garage to pop you on some £25 part worn’s.
What are we going to be reading next, I put Budget tyres on my Aston Martin DBS, because premium ones are a con?
Give the car some of the respect it deserves and it will look after you.
Then ask BMW the same question.
Then ask your insurance company the same question.
I will tell you now, they will all say NO!
Why will they say no? Because it is not safe that is why. There is a lot more difference to run flats than just the side wall.
At the end of the day, you own your car, and you do whatever you want too it. A comment was made earlier in this post about if you cannot afford to run it, you shouldn’t have brought it, and that in my honest opinion is spot on.
Run flat tyres are absolutely superb, providing you have a road infrastructure that is well maintained. UK roads are shocking, and as such run flats are a poor driving experience. Drive the same car, on the same tyres in say Germany, and you will hardly notice the runflats.
If you are going to make the change, change all 4. If you cannot afford to do this, then wait until you can. If you can’t see yourself being in a position to ever change all 4 at the same time, go and buy a Honda Civic and get Tony from the back street garage to pop you on some £25 part worn’s.
What are we going to be reading next, I put Budget tyres on my Aston Martin DBS, because premium ones are a con?
Give the car some of the respect it deserves and it will look after you.
You don’t become wealthy by throwing your money around! 
but on a serious note your tone of language is not acceptable on a forum where some of us are trying to have a sensible conversation. As I and others have stated some of us have mixed RFT with non RFT on different axles and have experienced no handling issues, where others have. let’s just leave it there and let people make there own mind up. Just accept that we all have different points of view.
but on a serious note your tone of language is not acceptable on a forum where some of us are trying to have a sensible conversation. As I and others have stated some of us have mixed RFT with non RFT on different axles and have experienced no handling issues, where others have. let’s just leave it there and let people make there own mind up. Just accept that we all have different points of view.SiJar said:You don’t become wealthy by throwing your money around!
Granted I probally owe you an apology , it was quite late & I was on the outside of a fair amount of alcohol so sorry , sadly im not wealthy either but trying to be reasonable Tires really are a safety item and I dont see why I should be exposed to risk because someone wants to save a few quid and I really struggle to understand why anyone would out themselves at risk for a few quid either , when ever I buy a car I investigate potentail costs and decide if its affordable (hence no Aston Martin) and if people are thinking tyres are expensive then they bought the wrong car