pass tire speed rating

[none67]

just curious, what happens AFTER you go pass the speed rateing on a tire? do they expand, or blow, or what?

 

[65fastback2+2]

the original manual for my stang says anything over 65 inflate higher than 35 lbs. But i think that was for those old tires. On todays radials, i think 35 is good. I know ive had mine up to 108 mph and the tires are at about 33-35 lbs.

 

[daveoxide]

just curious, what happens AFTER you go pass the speed rateing on a tire? do they expand, or blow, or what?

The speed rating on a tire is the maximum speed the tire will stay together as one without flying apart while maintaining that speed for a particular amount of time (I don't know what that time is though, unfortunately).

So if you have stock type radial tires they could be speed rated as low as 87mph, which is scary because if you took a jaunt to 100mph, more than likely, you could lose a tire ESPECIALLY if they weren't at their maximum rated psi. If tires aren't at their maximum rated psi, speed ratings and load ratings are both lower than stated (some more than others, depends on the tire).

So, for yourself and those of us driving around you, stay below the maximum rating of your tires OR get new tires that have a higher speed rating. I am running tires that have a W speed rating (168mph), and my Mustang is incapable of achieving those speeds, so I feel quite safe running those tires hot and hard at speed.

 

[none67]

thanks guys

btw, dave, what tires do you use? (also, your site is awsome)
I am trying to plan ahead, my car is still in restortion - but my 289 is really highwinding, and for the time being i have 2.79s; so for the time that i have them minus well have some fun.

 

[Red Barchetta]

...If tires aren't at their maximum rated psi, speed ratings and load ratings are both lower than stated (some more than others, depends on the tire)...

This is not quite accurate. Not to pick on you, but check out this link to Car & Driver for a good explanation on tire speed rating. From the link:

In the high-speed test, the basic methodology is unchanged. The tires are tested on a 67-inch-diameter drum in a chamber with the temperature controlled at 100 degrees. Since the round surface of the drum deforms the tire carcass more than a flat road would, a speed of 80 mph on a drum is the equivalent of from 85 to 90 mph on flat pavement.

The tires to be tested are inflated to 32 psi for standard P-metric tires (the “P” stands for passenger-car tire) and for tires without the P but with a letter speed rating (S, H, V, and others). Extra-load P-metric tires are tested at 38 psi. These conditions are unchanged from those of the old FMVSS 109 tests.

It's a good read.

 

[D.Hearne]

I wouldn't worry about exceding the speed rating, it's mostly there as a sales tool. Unless you're gonna somehow get to run your car at Daytona or Taladega, you'll never be able to run fast enough or long enough to blow the tire. The Highway patrol will get you long before the tires let go. Just as a reference, back in the late 80's I had my own 18 wheeler ( Peterbuilt what else LOL) and one night me and another driver "hooked up" heading west on I-10 from I-75 in Florida, It took us 3 hours to run from the I-75 junction, to Pensacola, a distance of about 290 miles. The only tire on my truck that didn't handle the run was a recap on the trailer, this one let loose just getting into P'Cola. None of these tires were "speed rated" Just ignore the speed rating.

 

[69 302/351c]

I've got 149mph V rated tires on my ...Saturn. Like it could break 100. Just got a good deal price wise, but they suck on wet roads and they don't like seams in the pavement.

 

[daveoxide]

This is not quite accurate. Not to pick on you, but check out this link to Car & Driver for a good explanation on tire speed rating. From the link: It's a good read.

I stand corrected . But if the tires aren't inflated to that 32 psi, then speed rating and load ratings wouldn't be at their maximum, right?

 

[daveoxide]

btw, dave, what tires do you use?

They are Yokohama AVS100's. They have superb grip in both wet and dry. They are a soft compound tire, so mileage isn't great, expect them to last 10,000 to 15,000 miles. They are an ultra high performance tire, and they are damn sticky! And because of my more extreme alignment and the fact that they have those big V-shaped treads, it tends to follow the grooves in the road, but it isn't a big deal.

 

[none67]

I wouldn't worry about exceding the speed rating, it's mostly there as a sales tool. Unless you're gonna somehow get to run your car at Daytona or Taladega, you'll never be able to run fast enough or long enough to blow the tire. The Highway patrol will get you long before the tires let go. Just as a reference, back in the late 80's I had my own 18 wheeler ( Peterbuilt what else LOL) and one night me and another driver "hooked up" heading west on I-10 from I-75 in Florida, It took us 3 hours to run from the I-75 junction, to Pensacola, a distance of about 290 miles. The only tire on my truck that didn't handle the run was a recap on the trailer, this one let loose just getting into P'Cola. None of these tires were "speed rated" Just ignore the speed rating.

Well i live in eastern canada, and the cops here are not NEARLY as bad as in the states. I went on a road trip down to washington DC (with my family; lots of stops in between) so i could easily get away with it on the "old" highways. But i gotta say you guys tend to drive "fast" (according to the speed limit) i was mostly on the New Jersy turn pike and the I-95 usally about 10-20mph over, but the jersy pike was HORRIBLE for traffic jams, we were in about 3 on the way back (bumper-to-bumper).

But what you are saying that something like the BF Good Year(15inch) radials (rated 112mph) can handle what?

 

[none67]

They are Yokohama AVS100's. They have superb grip in both wet and dry. They are a soft compound tire, so mileage isn't great, expect them to last 10,000 to 15,000 miles. They are an ultra high performance tire, and they are damn sticky! And because of my more extreme alignment and the fact that they have those big V-shaped treads, it tends to follow the grooves in the road, but it isn't a big deal.

soudns nice, but i don't think i can afford the 10,000-15,000 miles though. she will get drivin way to much.

what do you guys suggest? (15s, or 17s)

 

[daveoxide]

soudns nice, but i don't think i can afford the 10,000-15,000 miles though. she will get drivin way to much.

what do you guys suggest? (15s, or 17s)

I take that back, mileage is probably closer to 15,000 to 20,000 miles out of the tires. I drive my Mustang hard too, so you could get more than that out of them I'm sure. With tires, it's a give and take between mileage and performance, and in my case, I chose performance .

And as far as rim sizes go, don't forget 16's. They are a nice compromise between 15's and 17's. Good tires can still be had for less than $100 a pop, and you get some of the benefits of 17's like less tire flex and better handling. But ultimately, it depends on how you will be driving your car. Do whatever you want, as long as it makes you happy, that is what matters most.

 

[none67]

I take that back, mileage is probably closer to 15,000 to 20,000 miles out of the tires. I drive my Mustang hard too, so you could get more than that out of them I'm sure. With tires, it's a give and take between mileage and performance, and in my case, I chose performance ..

i aggree to the fullest, infact i keep the vid of your 67 doin that cool peelout in 2nd (up the hill) loaded on my puter at all times. i use it to compare to my mustang to all my import "friends".

as for the 16s i never really thought of them.. but i'll mostlikey get 15s because of the price (turning 16 next month (PERMENT WAAAHOOO!!!) and its already costing me both my nuts.. really as long as there 15,16,17 and chrome i don't care lol

 

[Red Barchetta]

I stand corrected . But if the tires aren't inflated to that 32 psi, then speed rating and load ratings wouldn't be at their maximum, right?

I couldn't tell you. That's a question for a tire engineer. As with everything else, heat is a tires enemy. I would ASSuME that different ambient temperatures would have an affect on tire reliability. Unless you're driving in the same conditions as in the testing process, the maximum rating could vary. With that assumption, the cooler the tire, the less likely it will fall apart. That's why you raise the psi when you have a heavier load on the tire. This keeps the tire sidewall from deforming more than normal while keeping a full contact patch on the ground, reducing heat build up. Once again, I'm no tire engineer (or any kind of engineer for that matter), but I think heat is the limiting factor. With increased speeds and loads, comes increase heat. Ultimately, I believe that is your limiting factor.