Tyres XL or not?

[SoloNomad]

Looking to replace my tyres sometime. I have Bridgestone Potenzas on the rear and Dunlop Bluresponse on the front (came like this from previous owners) tyres good but I can't get the front in Bridgestones or the rears in the Dunlops as they don't seem to make the sizes. I've read a lot of threads on here and elsewhere and getting matching front and rears is proving time consuming when looking at tyre suppliers, often they don't come up with the correct sizes so I have to search one size then try to find the other in a separate search. Anyway, when I do finally find matching pairs it often comes up with the rear 16s being 'XL' extra load, do I really need extra load and should I be selecting this for both front and rears? Reading up a bit on this suggests they will have stiffer sidewalls which could be good for the MR2 but also read this could lead to more tramlining??

[Carolyn]

The majority are insistent that all tyres should be the same brand and type.  I tend not to be so insistent.

The fronts do braking and steering and the rears do power delivery- so a tyre that's good at one, may not be so good at the other.

In other words I think it's ok to mix tyres so land as you don't do it on the same axle.

[JB21]

Go XL if possible, especially on the front to help with turn in and steering feel. No point fitting some squishy tyre to a mid engine sports car as it just defeats the object.

[Dev]

XL tires are poorly understood. XL tires are basically reinforced tires not necessarily stiffer for feel but because they are used in low profile applications it might be stiffer but it doesn't have anything to do with XL tires reinforcement because there are SL tires that are also low profile now that the technology has improved.

 It is the air that holds most of the load not the tire. When low profile tires came into the mix they needed a way for these tires to hold more load so the tires are reinforced to hold more air. As a result you cant use the same load chart for SL tires to calculate the load as XL tires generally need more tire pressure for the same load and there is a chart that calculates that. 


 It is perfectly fine to mix XL and SL tires as long as they can be adjusted to hold the load. On average the XL tires may need as much as an additional 4PSI as a SL tire but it depends on the tire and application. What is more dangerous is mixing tires because their characteristics vary and can vary at different temps as well as different situations. It might drive fine initially but when you need the tires the most in a case of accident avoidance the tires will lose its predictability and can be disastrous. For a race car its not so much of a problem but for a street car it would be a bad idea.

 Here is a tire load calculator that should help you.

https://tiresize.com/pressure-calculator/

[Gaz mr-s]

I read tyre tests to choose.  I discovered on Friday the 255 rears on my BM were almost at the wear mark.  I had contributed to a couple of current threads about tyres on here & JB21 mentioned Falken 510. I looked up tests & they completely backed-up what he said. there was a 15% off offer on ebay & Demon Tweeks had them, so a bit less painful than it could have been.

Falken ZE310 are well liked & there's a few I know of who have Hankook K125 (me included) & like them.  They fare well in tyre tests too.  The K125 rears have recently leapt up in price (high £90's) & that may be because they're getting scarce,- there is a new replacement coming out which I've been told is an improvement.

Lots of folk mention Toyo, but they rarely feature in tests which I'm deeply suspicious about.

I need a set for a new set of wheels, but it can wait until late spring.  Hankook or Falken likely. 

[SoloNomad]

Thanks all, interesting reading the replies. That pressure-calculator was an eye-opener as going up a size - 195mm front came out as 2psi lower than original pressure, for some reason I would have actually thought I'd need more psi!

In my searches I've mostly found Hankook K125s and Avon ZV7s in the right sizes, the rear 16s come in 'XL', I'll have to check if the fronts are available in XL, I'm sure the Hankooks are.

The Avons come out at a good price, saw them mentioned in the tyres.tyres,tyres thread a few times but not many mentions elsewhere - any good? Reviews a bit mixed online and not everyone who leaves a review drives something like an MR2.

[Gaz mr-s]

In my searches I've mostly found Hankook K125s and Avon ZV7s in the right sizes, the rear 16s come in 'XL', I'll have to check if the fronts are available in XL, I'm sure the Hankooks are.

The Avons come out at a good price, saw them mentioned in the tyres.tyres,tyres thread a few times but not many mentions elsewhere - any good? Reviews a bit mixed online and not everyone who leaves a review drives something like an MR2.

The ZV7 is an old tyre, & time has moved on, - it does not come out well in tyre tests.  (not punters reviews)

[105e]

The majority are insistent that all tyres should be the same brand and type.  I tend not to be so insistent.

The fronts do braking and steering and the rears do power delivery- so a tyre that's good at one, may not be so good at the other.

In other words I think it's ok to mix tyres so land as you don't do it on the same axle.

I absolutely agree with this, indeed i think it could be possible to mix them to gain an advantage..

[Dev]

Thanks all, interesting reading the replies. That pressure-calculator was an eye-opener as going up a size - 195mm front came out as 2psi lower than original pressure, for some reason I would have actually thought I'd need more psi!

In my searches I've mostly found Hankook K125s and Avon ZV7s in the right sizes, the rear 16s come in 'XL', I'll have to check if the fronts are available in XL, I'm sure the Hankooks are.

The Avons come out at a good price, saw them mentioned in the tyres.tyres,tyres thread a few times but not many mentions elsewhere - any good? Reviews a bit mixed online and not everyone who leaves a review drives something like an MR2.

Just keep in mind that its not about going up in size as much as its matching the load rating between tires. There are some 195 tires that need more air. 
As an example I use to have Falken tires that were 205 which required an additional 4PSI to hold the same load as the OEM 185. If I were to use OEM pressures it would be under inflated and the tire internal belts would damage. For my new tires which are SL but roughly the same size I now require 1PSI less air and these tires are far more stiffer in feel.


You need to match the load ratings like for like with the exception of XL tires which is calculated from a different chart for its load since they can be inflated with higher air pressures. The industry is confusing but the calculator works great.

One question that is interesting, why cant we inflate an SL tire to a higher pressure and achieve a higher load rating. Unfortunately it doesn't work that way as once the tire reaches a certain PSI, I believe 36psi for SL and 40PSI for XL its max load rating is achieved no matter how much more additional air you add.

[SV-3]

Thanks all, interesting reading the replies. That pressure-calculator was an eye-opener as going up a size - 195mm front came out as 2psi lower than original pressure, for some reason I would have actually thought I'd need more psi!

In my searches I've mostly found Hankook K125s and Avon ZV7s in the right sizes, the rear 16s come in 'XL', I'll have to check if the fronts are available in XL, I'm sure the Hankooks are.

The Avons come out at a good price, saw them mentioned in the tyres.tyres,tyres thread a few times but not many mentions elsewhere - any good? Reviews a bit mixed online and not everyone who leaves a review drives something like an MR2.

Have ZV7s on Chilli Red - they are fine.
Also have Avons on my daily twin turbo car - they are also fine.

[Petrus]

The majority are insistent that all tyres should be the same brand and type.  I tend not to be so insistent.

The fronts do braking and steering and the rears do power delivery- so a tyre that's good at one, may not be so good at the other.

In other words I think it's ok to mix tyres so land as you don't do it on the same axle.

I absolutely agree with this, indeed i think it could be possible to mix them to gain an advantage..

I would not unless the same tyre with softer compound front and then only if the softer does not have a higher temp operating window.
As Dev observes, on the road you want the rubber to be predictable above all.

[Gaz mr-s]

I absolutely agree with this, indeed i think it could be possible to mix them to gain an advantage..

It possibly might be possible, if one was trying different widths instead of the standard stagger.

But unless an individual has money to throw away experimenting with different types, that's the only way to find out.

This is a distant analogy.... I used to race r/c cars. Whether it was slick rubber on tarmac, or a type of foam, or spiked rubber that was made in different hardnesses (compounds), you didn't mix types.  The balance of grip front-back was altered & to get it to work would have meant suspension changes, & maybe just a blind alley to nowhere....   I'm not aware of any really good racers (I was NOT in that bracket) doing it.

A car with a rear weight bias, - asking for trouble IMO.

[Dev]

I would not unless the same tyre with softer compound front and then only if the softer does not have a higher temp operating window.
As Dev observes, on the road you want the rubber to be predictable above all.

 There are multitude of reasons why you shouldn't mix. Two tires even if they appear to have the same compound will react differently at different temps as they change dynamically.
 This will not play nice when the fronts stick and the rears are not warmed up enough. It also doesn't play nice if one set is overheated and becomes greasy.
 
 Thats just part of it but the biggest one is the tire construction. If you have tires with soft side walls and you mix them with tires that are more responsive it can make the car react poorly and you can lose control. 

 Im sure if you mix and match enough times you might find tires that work in harmony but that is very expensive way to find out and you are most likely to not have a matching set that is above all safe for the roads.


 

[JB21]

I use different size, brand and compound slicks on track. Not really to tune the handling of the car, but more of what was available on ebay at the time before a track day.

Fronts are 190/570/15 MRF slicks in hard compound.

Rears are 200/580/15 Hankook slicks in medium compound.

If you look at it from a handling POV  then my car 'should' be set up for understeer. In reality its a nice neutral set up. A hint of understeer maybe but this is what Toyota was going for with the car I think. The car is very manageable at the limit.

Both sets seem to heat up at the same time and have nice even temps across the tyres.

Picture below of the slicks compared to my AR1's. You notice the slicks are very similar in width even though the width numbers a different, especially the rears.

195/50/15 v 190/570/15



225/45/15 v 200/580/15



And the stagger of the slicks

[Ardent]

Taking on board all of the opinions and voices of experience above.
On public roads, up to the legal limit.
Can, or rather, how likely would the differences come into play in this scenario?
Or do they only really manifest when driving 10/10ths. Which is not usually considered wise on the public highway.

[Petrus]

Taking on board all of the opinions and voices of experience above.
On public roads, up to the legal limit.
Can, or rather, how likely would the differences come into play in this scenario?
Or do they only really manifest when driving 10/10ths. Which is not usually considered wise on the public highway.

Grip yes. The feel no; comfort, noise, responsiveness, even ´tramlining´ vary and that is pretty much pick your choice within the road legal boundaries.

[Dev]

Taking on board all of the opinions and voices of experience above.
On public roads, up to the legal limit.
Can, or rather, how likely would the differences come into play in this scenario?
Or do they only really manifest when driving 10/10ths. Which is not usually considered wise on the public highway.

 It will certainly manifest in an accident avoidance scenario for sure where the tires are taken to its limits in both dry and especially wet. Not for overall grip but for its characteristics of how it lets go to slide out progressively  or the ability to recover by being forgiving. You don't know how the car will react when it is upset not knowing that the limits are lowered greatly. At least with a matching set it is far more predictable because the tires will have the same character at the same temps and weather conditions.

Edit: Just to make clear it is not my opinion not to mix tires. It primarily comes from the tire and vehicle manufactures recommendations for the reasons I gave. If in doubt consult with the tire manufacture or an experienced tire shop. A simple google search will have plenty information about the dangers of mixing in a real road situation. 

[SoloNomad]

This has made for some interesting reading.

On my other cars and my currant van it was simply a case of choosing something reasonable as I could just get 4 the same if needed, I think that's where the staggered wheels of the FL MR2 throws a spanner in the works. I've gone on a couple of manufacturers websites like Bridgestone, put in the car details, to find that they recommend a front tyre but don't have a matching rear in the size needed. Several times I've found a good tyre when going through reviews only to find they don't do them in the sizes we need at all. Probably go with Hankooks or Falkens when the time comes and get matching load/speeds if I can.

[JB21]

This has made for some interesting reading.

On my other cars and my currant van it was simply a case of choosing something reasonable as I could just get 4 the same if needed, I think that's where the staggered wheels of the FL MR2 throws a spanner in the works. I've gone on a couple of manufacturers websites like Bridgestone, put in the car details, to find that they recommend a front tyre but don't have a matching rear in the size needed. Several times I've found a good tyre when going through reviews only to find they don't do them in the sizes we need at all. Probably go with Hankooks or Falkens when the time comes and get matching load/speeds if I can.

I use Rainsport 5's on my FL wheels. 195 front and 205 rears in XL rating. For the money they are excellent and have outstanding grip in this currency weather.

[Petrus]

I think that's where the staggered wheels of the FL MR2 throws a spanner in the works.

That´s what I found with Fedima competition rubber.

Thanks for the photos btw @JB21

[Zxrob]

Taking on board all of the opinions and voices of experience above.
On public roads, up to the legal limit.
Can, or rather, how likely would the differences come into play in this scenario?
Or do they only really manifest when driving 10/10ths. Which is not usually considered wise on the public highway.

^^^^ This

Most folk wont be driving @50% of the cars/tyres performance, yet alone 10/10ths
Two good matching on the front and two good matching on the rear, albeit different makes will be better than  4 shite/old ones all round

Rob

[Petrus]

A set of good, albeit different tyres on the same axle

I suspect that this came out different than you meant it ;-)

[Zxrob]

A set of good, albeit different tyres on the same axle

I suspect that this came out different than you meant it ;-)

Indeed,  edited

Rob

[SoloNomad]

I use Rainsport 5's on my FL wheels. 195 front and 205 rears in XL rating

I've read about Rainsports being good - you've gone up a size on the front and down a size on the rear, do you have the same profiles of 55 and 45 ?

I do wonder about going up or down in size and profile, can't imagine it making a huge difference when talking about 10mm or 5%.

[Petrus]

I do wonder about going up or down in size and profile, can't imagine it making a huge difference when talking about 10mm or 5%.

Over here 3% is the legal limit of ´equivalent´.