W and Y rated tyres

[Auckland]

Good morning M`Lords, Ladies and Gentlemen.

I have a 2 liter Skoda Superb with 18" wheels.

The tyre size:

225/40/18. Except the front tyres are Y rated and the rear tyres W rated.

I`d like to know what the difference between the tyres is please?

Is it the done thing to have two different rated tyres on the car at the same time?

I`m looking forward to hearing from you.

Cheers from the South Pacific

[mnehls86]

Not sure why they would be different, seems weird. That`s an 18 mph speed rating difference. I hope you are only pushing those ratings at the track.

[EVOlved]

From tirerack .com:

Mixing Tires

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As a general rule, tires should not be mixed on any vehicle unless specified as acceptable by the tire or vehicle manufacturer. Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes, and use identical tires on all of their vehicle`s wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires, or mix run-flat tires with non-run-flat tires.

This is one of the reasons that it is desirable to have all of a vehicle`s tires wear out at the same time. It`s confirmation that the vehicle design, driving conditions and maintenance practices worked in unison to equalize tire wear and performance. It also lets drivers know they got their money`s worth out of the current tires and allows them to choose a set of replacements that will either maintain the Original Equipment (O.E.) tires` capabilities, or help tune the vehicle`s qualities to even better suit their needs.

Unfortunately wearing out all tires at the same time isn`t always possible. Sometimes vehicle design, the use of differently sized tires on front and rear axles, insufficient maintenance and/or driving conditions conspire to prevent it from happening.

If a vehicle`s tires don`t all wear out at the same time, drivers are typically forced to decide whether they should purchase a new set of tires (forfeiting the worth of the two tires not fully worn out) or just a pair of replacements. While purchasing a new set of tires is best because it will maintain the handling balance engineered into the vehicle while restoring poor weather traction, it is also more expensive. And while purchasing a pair of replacement tires reduces immediate expense, it brings with it the options of choosing exact, equivalent or alternative tires.

Of the three, the best choice is to select the exact tire currently on the vehicle. This assures that the tire`s physical dimensions, internal construction, tread design and tread compound are equal to the tires being replaced.

The second option is to choose equivalent tires from the same tire performance category that share the same speed rating, handling and traction characteristics of the original tires. While this isn`t as desirable as selecting the exact tire currently on the vehicle, it can become necessary when the original tires are no longer available.

The third option, choosing alternative tires, should only be considered as a temporary solution in an emergency situation. Using alternative tires from different tire performance categories, with alternate sizes or different speed ratings can unbalance the vehicle`s handling in poor weather or when pushed to the limit in an emergency.

Because tires play such an important role in every vehicle`s comfort qualities and handling capabilities, it is always best to drive on tires that are identical in every detail, including tire brand, model, size and remaining tread depth. Anything else involves some type of compromise.

Personally I worked in the tire industry for almost 10 years and this is of the utmost importance on AWD and 4WD vehicles. As it can actually mess with those systems.

You are saying the vehicle came from the factory this way??

[GearHead_1]

You certainly should feel a difference between those 2 ratings when cornering. The Y speed rated tire will feel stiffer (given the same sidewall height) than the W. It`s not just an issue above 168 mph as some may think. These two speed ratings will feel different across the performance spectrum. If you want to prove this to yourself, go push your car a bit through the twisties. Then do a straight rotation front to rear and do it again. I`d be surprised if you couldn`t feel a difference. I don`t know of anyone in the tire industry that would recommend mixing the two different service descriptions.

[Swanicyouth]

It seems to me, Continentals and Michelins are the best performance tires. It`s all a matter of preference - but I don`t like any tire whose name ends in a vowel: Toyo, Yokohama, Sumitomo, Kumho, etc... Cheap tires - with cheaper sidewalls. Probably best left for a tire swing.

[Auckland]

Hi there. Thanks for your input. I rarely drive over 100k`s. 120k`s max and that is extremely rare. All city driving. The tyres are Bridgestone-made in Poland.

[Auckland]

The car arrived with Continentials which don`t last too long in New Zealand. I only got 65,000k`s out of the rear tyres and 70,000k`s out of the front tyres. The Continentials cost NZ$800.00 each which is very expensive for me. The Bridgestone`s were NZ$270.00 plus fitting etc.

[The Driver]

What`s your top speed?

[Auckland]

What`s your top speed?

Hi there. I`m a paragon of virtue! I`ve never had the car above 120k`s. I can`t afford the fine if I`m caught.

[The Driver]

Hi there. I`m a paragon of virtue! I`ve never had the car above 120k`s. I can`t afford the fine if I`m caught.

Then W is your answer. y is overkill for any street car, even tracked ones.

[EVOlved]

But they still shouldn`t be mixed if possible to avoid. Especially if the car is AWD like I stated before. A lot of the time different speed rating means different tread pattern, different circumference, and different rolling resistances.

[paul huryk]

You certainly should feel a difference between those 2 ratings when cornering. The Y speed rated tire will feel stiffer (given the same sidewall height) than the W. It`s not just an issue above 168 mph as some may think. These two speed ratings will feel different across the performance spectrum. If you want to prove this to yourself, go push your car a bit through the twisties. Then do a straight rotation front to rear and do it again. I`d be surprised if you couldn`t feel a difference. I don`t know of anyone in the tire industry that would recommend mixing the two different service descriptions.

Not true at all.

A tire`s sidewall stiffness is due to construction and materials, not the speed rating necessarily. Some tires like Michelins have stiffer sidewalls than Continentals (for example) and yet have the same speed rating.

Now running 2 different tires on the front and rear can make a difference in handling, but not night and day.

While I wouldn`t suggest mixing speed ratings, most cars that only do 70 to 75 at the most on the highway would have no issues with a 168 tire on one axles and a 186 tire on the other.

BTW, there also a (Y) rating, which is 186+, which is only available in a few, select tires.

[GearHead_1]

You certainly should feel a difference between those 2 ratings when cornering. The Y speed rated tire will feel stiffer (given the same sidewall height) than the W. It`s not just an issue above 168 mph as some may think. These two speed ratings will feel different across the performance spectrum. If you want to prove this to yourself, go push your car a bit through the twisties. Then do a straight rotation front to rear and do it again. I`d be surprised if you couldn`t feel a difference. I don`t know of anyone in the tire industry that would recommend mixing the two different service descriptions.

Not true at all.

A tire`s sidewall stiffness is due to construction and materials, (is exactly what determines a tires potential/speed rating) not the speed rating necessarily. Some tires like Michelins have stiffer sidewalls than Continentals (for example) and yet have the same speed rating.

Now running 2 different tires on the front and rear can make a difference in handling, (Thank you, you`re making my point!) but not night and day. (Your words)

While I wouldn`t suggest mixing speed ratings, most cars that only do 70 to 75 at the most on the highway would have no issues with a 168 tire on one axles and a 186 tire on the other.

BTW, there also a (Y) rating, which is 186+, which is only available in a few, select tires.

Not sure which part of my comment you don`t believe to be true. Take two different speed rated tires from the same manufacturer, same profile/sidewall height and run them on opposite axles. Go run the car through the twisties (hard, not 75 mph straight down the middle, push them a bit) and then rotate the tires front to rear. If you don`t feel a difference you don`t know what you`re trying to feel. Obviously this is only possible if the wheels are the same size. Do the same with just one oddball tire and the effect is more noticeable. Would your grandma in her 82 Impala notice a difference? Probably not.

I mentioned the 168 mph rating as the limit of the lesser tire. I think most participating in this thread understood the Y rating was higher. You don`t have to make this comparison with W & Y tires. If you do the same with an S and a T it`s still quite obvious. Point the vehicle straight down the road you won`t notice a thing, lean on it a bit you`ll know.

By the way construction and materials are what determine a tire`s speed rating so I`m not sure of your point. A higher speed rated tire will have a stiffer sidewall (when compared within a manufacturer`s line) than an a lesser rated tire. Just like the UTQG rating for tire wear the numbers are only relevant within a single manufactures line. A sidewalls stiffness is subjective and can`t be compared between manufacturers. There is no rating for stiffness, it`s simply the result of "construction and materials". The result of these better materials and processes is a higher speed rating and a stiffer sidewall is a byproduct. You were the one that said night and day though if you really DRIVE (as opposed to cruising the boulevard) a performance car that may not be a bad description.

Is there an exception to this rule? Perhaps. There are few absolutes. I may have wrongly assumed that we were talking about tires that were all from a single manufacturer but beyond that I stand by my statement.

[512detail]

so are you planning on driving this like those vehicles on the firestone commercials?

if not then the difference will be negligible

now v to w/y, yes that will be more noticeable. so yes there will be a difference, as well stated and argued above, but I really doubt you will be driving on that threshold, but then again, I don`t know you from Adam.

[paul huryk]

Not sure which part of my comment you don`t believe to be true. Take two different speed rated tires from the same manufacturer, same profile/sidewall height and run them on opposite axles. Go run the car through the twisties (hard, not 75 mph straight down the middle, push them a bit) and then rotate the tires front to rear. If you don`t feel a difference you don`t know what you`re trying to feel. Obviously this is only possible if the wheels are the same size. Do the same with just one oddball tire and the effect is more noticeable. Would your grandma in her 82 Impala notice a difference? Probably not.

I mentioned the 168 mph rating as the limit of the lesser tire. I think most participating in this thread understood the Y rating was higher. You don`t have to make this comparison with W & Y tires. If you do the same with an S and a T it`s still quite obvious. Point the vehicle straight down the road you won`t notice a thing, lean on it a bit you`ll know.

By the way construction and materials are what determine a tire`s speed rating so I`m not sure of your point. A higher speed rated tire will have a stiffer sidewall (when compared within a manufacturer`s line) than an a lesser rated tire. Just like the UTQG rating for tire wear the numbers are only relevant within a single manufactures line. A sidewalls stiffness is subjective and can`t be compared between manufacturers. There is no rating for stiffness, it`s simply the result of "construction and materials". The result of these better materials and processes is a higher speed rating and a stiffer sidewall is a byproduct. You were the one that said night and day though if you really DRIVE (as opposed to cruising the boulevard) a performance car that may not be a bad description.

Is there an exception to this rule? Perhaps. There are few absolutes. I may have wrongly assumed that we were talking about tires that were all from a single manufacturer but beyond that I stand by my statement.

The point of higher rated tires having more stiff sidewalls. S & T rated tires are low performance pedestrian tires with lower traction and higher wear ratings, of course they won`t handle as well in the same size as a W or Y tire - then again, try to find these all in the same size...

I was referring to comparing a W to a Y tire, which are going to be close in most respects - temp and traction rating may be identical. The difference can be as little as a slightly lighter tire that allows heat to dissipate quicker and thus allowing a higher rated speed, or it could be a stronger material for the belts inside that can keep together at higher speeds and temps. Neither will necessarily add to sidewall stiffness.

I have two sets of tires on identical wheels here in my shop. One has a set of falken 615Ks, the other Continental Extreme contacts in the same 275-40-17 size. Both are the same speed rating, same temp and traction ratings. But the Falkens are 3lbs heavier each and have a much less wide tread (even with the same 275mm section width). The Continentals have less stiff sidewalls and ride noticeably better, but can`t match the Falkens for grip. Always a tradeoff...

Let`s not forget the load rating, which is very important for identifying a tire to be able to keep together at speed. A 94 rating in the same size is not the same as a 102 or 105 when it comes to high speeds. In max speed cars, you want to be around 50% of the max load rating (or less) to assure the tires won`t come apart.