I found a nail in my tire today and had it taken to pepboys to get it pluged. they repaired it but said I know longer had a Z speed rating. They suggested I get a new tire, or don't go over 80mph. Should I really be worrying about this?
The car sees 65-85mph regurlary.

 

What size tires do you have?

 

512s don't come in Z rating AFAIK, but regardless of tire make, size or speed rating, the rule of thumb is, once the tire has been plugged, that high speed tires become a "standard" tire (my guess that's no better than S or T rated), but that really depends on the manufacturer (and who fixed the tire). 85 mph should be fine if the plug was done properly, but I personally wouldn't go too far past that.

 

Says who? Some 512s come w/ Z rating.

 

Says Falken. Find me a Z rated tire here http://www.falkentire.com/tires_512_sizes.htm

 

I'm running 245/40/18s and they are Z rated. If you don't belive me, I'll take a picture and post it.

There are many other sizes which are Z rated also.

 

Y and W are subratings (lack of better term) on Z tires.

From Tirerack

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.

W 168 mph 270 km/h Exotic Sports Cars
Y 186 mph 300 km/h Exotic Sports Cars

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

225/50ZR16 in excess of 149 mph, 240 km/h
205/45ZR17 88W 168 mph, 270 km/h
285/35ZR19 99Y 186 mph, 300 km/h

Most recently, when the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:

285/35ZR19 99Y 186 mph, 300 km/h
285/35ZR19 (99Y) in excess of 186 mph, 300 km/h

 

In a nutshell, "Z" doesn't mean what it used to anymore, and they just put the "Z" in with the size whenever it is a tire that is actually "W" rated (149 mph) or higher, mainly because it looks nice.

 

Makes me wonder how "fresh" your tires were when you bought them.

 

What do you mean fresh?

Check out this link. It's more accurate than the one you posted

http://www.1010tires.com/tire.asp?ti...=Ziex+ZE%2D512

 

Ive done 100+ on pluged tire and never had anyproblems. Pep boys has to tell you this for insurance and liability reasons but you should be fine...

 

So, you believe that 1010 tires know more about Falken tires than Falken themselves... All that link tells me is that 1010 has a stock of tires at least a couple of years old.

p.s. Fresh as in not oxidized. Rubber deteriorates with time. Any Z rated 512 on sale by anyone at this point in time have been around for a couple of years, minimum. Add a little ozone pollution (hopefully no UV light exposure, but who knows, I see a lot of tires in racks outside of mom and pop shops) and presto, tires half way into landfill. Tires should be replaced 5-6 years after manufacturing, regardless of mileage, because of oxidation. Anyone who owns a trailer should know this.

 

To answer your comment again, some 512s come w/ z rated

 

"Came" w/ Z rated. If you buy a Z rated 512 today, it's NOS (New Old Stock, not the other NOS). The new, "fresh" 512s are W and Y rated.

 

Falken 512 still say 'Z' on them. My friend has new 512's. She had to wait for them to come direct from Falken. They read 225/55ZR17 97W on the side.

 

Taken directly from Falkens data book:

For tires with speed symbols W and Y, "ZR" may or may not also appear within the size designation. For tires with a maximum speed above 186 MPH, a "ZR" must appear in the size designation. Examples of similar size markings, with and without service descriptions, and showing different maximum speeds, are shown below:

Example:

Tire Designation Maximum speed
p275/40R17 93W............................................... .....168MPH
P275/40R17 93Y............................................... .......186MPH
P275/40ZR17 93W............................................... ....168MPH
P275/40ZR 93Y............................................... .........186MPH
P275/40ZR17 (NO SERVICE DESCRIPTION)............ABOVE 149MPH

Regards,

Your friendly Falken Tire Service Rep...

 

I was trying to say something like that... The "Z" in the tire size, like in 215/40ZR17, doesn't really mean very much these days. I'm pretty sure that the practice of giving the tires no speed designation other than just Z isn't done anymore, and the true speed rating is given next to the load rating. Besides that, if you ran across a tire that just had Z, it doesn't mean that you could run 300 mph on it. Like in the old days of the Z speed rating, it's only used to VAGUELY mean some speed over 149 mph. These days they mainly keep the letter there because it looks nice.

 

Bingo. The speed rating follows the load index, a convention that's been in use for about 5 years now. Anyone who's got Z rated 512s just don't know what tires they are driving on or bought a set that's been laying around for a while.