Tire's speed rating
 

If my speed rating says it cannot exceeds 190km/h, does that mean I can't drive it more than 190km/h at all or can't drive it more than 190km/h for a certain period of time non stop?

i would NEVER go over the speed rating, why risk it.? even if on the track or watever, just get some REAL tires with proper speed rating, than take ur car to that speed if you really wonna see.....baby jesus?

tire speed ratings are for a maximum speed sustained for 24 hours

if your thinking about going 190 you better be on a track, most tracks asks for proper equipment. Highly suggest you get some proper track tires before you go

I don't know about the 24h thing, but it's a number that you don't want to exceed for any extended period... pretty sure it's less than 24h for passenger vehicles.

yup, never heard tat 24hr thing

For North America tires have to pass some sort of SAE certification for a certain speed.

I have no idea what that is, but to be European ECE certified, the tire must be able to sustain the speed for 10 minutes without failure. That's a brand new tire, operating at ambient room temperature. If your tire is older, it's degraded and will retain less of it's speed capability, if the temperature you are using it in is higher then the test environment, ie. hot summer track, the speed capability of the tire is again lowered.

If you have a plug & patch repair, your speed rating is supposedly lowered by only 1 tier per repair, I was told this by a tire tech at Kal Tire, but I really have my doubts on this. Anyways, basically, if your tire is rated to 190km/h, it is telling you DO NOT EXCEED 190km/h FOR ANY PERIOD OF TIME