19 Apr

What’s a service description?

Service description and speed rating

Hi Blog World,

I promised you an explanation of Speed Ratings.

The key is that the tire has the capability to do the speed it is associated to.  As I put in another post, generally speaking, a tire with a higher speed rating handles better delivering better grip in cornering, accelerating, and braking.  A common thought is that someone doesn’t need this.  Do you really want to stop slower rate?

I grabbed this chart from our website since it is so complete.  Click the chart to see it enlarged.

The most basic way you can think of how these work and how they will mix into different vehicles is nothing more than a equals to or greater than approach =>.

Let’s say we have a vehicle and it has 91S service description.

This means that a tire that has a like speed rating S, in this case, will be perfectly fine for the vehicle.  In addition, from the above chart, you can also use speed ratings T, U, H, V, W, Y, (Y), or Z.   All these will work with this vehicle.  Now, don’t let Z speed rating confuse you with W and Y.  W and Y rated tires are Z rated and will often times say ZR along with the W and Z rating.

Likewise for the Load Index part of the Service Description, any value higher than or equal to 91 will suffice.

In short, you can always go to higher load or speed rating, but you shouldn’t go lower.

18 Apr

I don’t drive over 100 mph

Speed ratings, What the heck?

You walk into the tire store and the sales person tells you that you need a certain speed rating for your car.

You say, “What does that mean?”

She says, “Well, your car came with an H rated tire, you need to stick with that.”

You reply, “You haven’t answered my question, what does it mean?”

She says, “It means the tire can safely travel 130 mph.”

“WHO’s gonna’ drive that fast, not me, I don’t need that!  Give me something else.”  You say.

I have been in the tire business for over thirty years.  I have heard this statement many times.  I have said what the hypothetical saleswoman said many time too, but there really Is more to it.  Does the Speed rating only have to do with speed?  And, should you care?

The answer to the second one is yes, you should.  Generally speaking the higher the speed rating of the tire, the better the tire will handle.  This is not always the case but is generally a good standard to live by.  Therefore, you really should maintain or increase the speed rating of the tire on your vehicle.  If we were to have a braking or cornering rating on the tire, would you willingly downgrade that? No, never.  So why would you downgrade the speed, or as I was taught many years ago “performance rating” of your tire?