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Discussion Starter #1
I'm having tires noise in the front. I currently have 225/40RZ/18, Y rating (186mph) , 92 load.

Is it okay to replace them with 225/40R/18, W rating (168 mph), 92 load?
Max speed I drive is 75mph on the highway.
 

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Administrator 2009 SLK 55 AMG/Founding member 2006
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I'm having tires noise in the front. I currently have 225/40RZ/18, Y rating (186mph) , 92 load.

Is it okay to replace them with 225/40R/18, W rating (168 mph), 92 load?
Max speed I drive is 75mph on the highway.
You should be able to. The numbers are all the same except for the top speed. Be aware that the top speed involves different compounds and belting arrangements. The handling might be a little different if you are a spirited driver. Otherwise you probably will not see a significant difference.
 

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Discussion Starter #5
Oh okay. I averaged around 23mph city, 30 on the highway so I don't think I'm a spirited driver.

You should be able to. The numbers are all the same except for the top speed. Be aware that the top speed involves different compounds and belting arrangements. The handling might be a little different if you are a spirited driver. Otherwise you probably will not see a significant difference.
 

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It doesn't show speed rating?! I already know the tires size.
it shows what other size tires can fit on your car.
that includes speed rating, etc, no?
isn't that what you are asking?
 

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Discussion Starter #7
No it doesn't. I'm asking if I could put 'W' speed rating on my car instead of Y rating which I currently have.

it shows what other size tires can fit on your car.
that includes speed rating, etc, no?
isn't that what you are asking?
 

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you can use any letter really just don't exceed the letters speed rating
 

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Yes, no insurance problems in the US, most MBs in the US are sold with "H" rated tires (and are limited to 130mph). Don't change the size that will affect dynamics.

Your car is limited to 155mph, so W is perfectly fine.
 

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I'm agreeing with pretty much every one else here...as long as you don't change tire size, and keep to the speed rating you'll be fine...as noted the cars are electronically limited to 155 mph (at least here in the states)...I'm running Firestone Indys rated to 168...

Sent from my SM-T550 using Tapatalk
 

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I'm agreeing with pretty much every one else here...as long as you don't change tire size, and keep to the speed rating you'll be fine...as noted the cars are electronically limited to 155 mph (at least here in the states)...I'm running Firestone Indys rated to 168...

Sent from my SM-T550 using Tapatalk
Unless you have the P 30 option and then the electronic limiter is removed.
 
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