If I'm not badly mistaken, the speed rating is tested at ambient temperature (~70°F) in a lab, i.e. perfect conditions.
Going down one speed rating OK?
- Thread starter rationull
- Start date
- Status
Originally Posted By: Rolf
Tire manufacturers have been selling automobile manufacturers higher speed rated tires at very reasonable prices knowing that there is a high probability that the owner will replace them with the same tires.
Like Capri mentioned, it is the auto makers that requested such tires. And the auto makers did this to increase the margin of safety (higher speed rating, higher load rating) so that the tires don't run close to their limit, and therefore to minimize overheating and blowouts even if you happen to overload your vehicle or run it at lower PSI (the Explorer fiasco).
Tire manufacturers have been selling automobile manufacturers higher speed rated tires at very reasonable prices knowing that there is a high probability that the owner will replace them with the same tires.
Like Capri mentioned, it is the auto makers that requested such tires. And the auto makers did this to increase the margin of safety (higher speed rating, higher load rating) so that the tires don't run close to their limit, and therefore to minimize overheating and blowouts even if you happen to overload your vehicle or run it at lower PSI (the Explorer fiasco).
Originally Posted By: Quattro Pete
... (higher speed rating, higher load rating) ...
I'm not really seeing that in the lists of tires on TireRack. To my view it looks more like load rating is determined by size. The 195/60R15s I'm looking at now come in 87 and 88 load range (I'm seeing both in H and in V rated). The 205/55R16s I looked at previously for another car came in 89 and 91 primarily, even H rated tires.
... (higher speed rating, higher load rating) ...
I'm not really seeing that in the lists of tires on TireRack. To my view it looks more like load rating is determined by size. The 195/60R15s I'm looking at now come in 87 and 88 load range (I'm seeing both in H and in V rated). The 205/55R16s I looked at previously for another car came in 89 and 91 primarily, even H rated tires.
Well, what I meant is that they started recommending larger/wider tires, and with that comes higher load rating, higher than what the additional weight of new cars would typically suggest.
Oh, sorry. I misread your post as saying "higher speed rating implies higher load rating" instead of "higher speed rating and higher load rating". I see it now 
Originally Posted By: rationull
. . . I'm trying to save a bit more on this purchase since it's my GF's money, not mine . . .
That says a lot about this process.
I guess it all boils down to this: Going down to an H will reduce the safety margin below what Volvo specified. If you're going to be taking care of these tires - keeping them properly inflated year-round, not over driving or overloading them - than an H should still be fine.
But if you're not going to be taking care of them, and it's not your car to begin with, do you want that responsibility and risk if the GF abuses them and then has a problem? GFs tend to be great at abusing cars.
If it were my 850, I could live with an H. But for someone else who has to drive on it, I always lean toward the safer option.
. . . I'm trying to save a bit more on this purchase since it's my GF's money, not mine . . .
That says a lot about this process.
I guess it all boils down to this: Going down to an H will reduce the safety margin below what Volvo specified. If you're going to be taking care of these tires - keeping them properly inflated year-round, not over driving or overloading them - than an H should still be fine.
But if you're not going to be taking care of them, and it's not your car to begin with, do you want that responsibility and risk if the GF abuses them and then has a problem? GFs tend to be great at abusing cars.
If it were my 850, I could live with an H. But for someone else who has to drive on it, I always lean toward the safer option.
I think I wasn't clear on that point. She drives it and she will be buying the tires, but I take care of it (including keeping the tires at pressure). She does not abuse it, and has been driving with the H rated tires it came with for the past 30k miles without issue.
A cheap way to hype a car's image, put higher speed rated tires on it. Oh, how do the margins on higher speed rated tires work? Do the tire shops make more the higher the rating?
Do you honestly believe a few extra nylon belts and firmer polymers actually quadruple a tire's manufacturing costs?
Didn't think so either.
Didn't think so either.
Lower speed rate does lower performance: braking distance is longer, straight line and lateral acceleration is slower, steering response is slower ... I know these effects because I tried several lower speed rates, from H down to T and S, for V rated '94 LS400.
As long as I have the tires inflated few PSI above placard but below max pressure on side-wall, the car was safe to drive up to 100-110 MPH on trips to Vegas in summer, even with S rated tires.
Just be sure to get the tires with max pressure higher than on placard.
As long as I have the tires inflated few PSI above placard but below max pressure on side-wall, the car was safe to drive up to 100-110 MPH on trips to Vegas in summer, even with S rated tires.
Just be sure to get the tires with max pressure higher than on placard.
This must be the thread for myths. Here's another one:
Originally Posted By: HTSS_TR
.......
As long as I have the tires inflated few PSI above placard but below max pressure on side-wall, the car was safe to drive up to 100-110 MPH on trips to Vegas in summer, even with S rated tires.
.......
There are quite a few things that affect the speed capability of a tire.
1) Inflation pressure: John Baldwin published a study of the speed rating of tires at different inflation pressures and found that the lower the inflation pressure, the lower the speed capability. He adjusted the load according the the inflation pressure. He found as much as a 2 step drop in speed capability.
2) Heat: Tires are tested for speed rating in a room at 70°F. The tire only has to maintain the speed for 1 hour. Increases in ambient temperature reduce the speed capability. I can't remember who did the study, but it was found that temperatures that are experienced in the US desert Southwest (which would include Las Vegas) can adversely affect the speed capability by as much as 2 steps.
3) Age: John Baldwin also published a study on tire aging and found that 4 year old tires - even unused tires - has lost some speed capability - as much as 2 steps.
What I take from all of this is that there are circumstances where a tire could lose as much as 6 steps in speed capability(may be more!). Put another way, a V rated tire might only have an R capability (106 mph). I can't tell for sure, but maybe this is why vehicle manufacturers are specifying V rated tires on what appears to be generic 4 door sedans.
Originally Posted By: HTSS_TR
.......
As long as I have the tires inflated few PSI above placard but below max pressure on side-wall, the car was safe to drive up to 100-110 MPH on trips to Vegas in summer, even with S rated tires.
.......
There are quite a few things that affect the speed capability of a tire.
1) Inflation pressure: John Baldwin published a study of the speed rating of tires at different inflation pressures and found that the lower the inflation pressure, the lower the speed capability. He adjusted the load according the the inflation pressure. He found as much as a 2 step drop in speed capability.
2) Heat: Tires are tested for speed rating in a room at 70°F. The tire only has to maintain the speed for 1 hour. Increases in ambient temperature reduce the speed capability. I can't remember who did the study, but it was found that temperatures that are experienced in the US desert Southwest (which would include Las Vegas) can adversely affect the speed capability by as much as 2 steps.
3) Age: John Baldwin also published a study on tire aging and found that 4 year old tires - even unused tires - has lost some speed capability - as much as 2 steps.
What I take from all of this is that there are circumstances where a tire could lose as much as 6 steps in speed capability(may be more!). Put another way, a V rated tire might only have an R capability (106 mph). I can't tell for sure, but maybe this is why vehicle manufacturers are specifying V rated tires on what appears to be generic 4 door sedans.
Originally Posted By: labman
A cheap way to hype a car's image, put higher speed rated tires on it. . . .
I don't think Volvo plays that game. On a model like the 850, the emphasis was on safety, not speed.
However, on many turbo 850s, the car can outrun an H speed rating. And on the recent R models, they specified Y speed/95 (XL) load rated tires - and they need 'em.
A cheap way to hype a car's image, put higher speed rated tires on it. . . .
I don't think Volvo plays that game. On a model like the 850, the emphasis was on safety, not speed.
However, on many turbo 850s, the car can outrun an H speed rating. And on the recent R models, they specified Y speed/95 (XL) load rated tires - and they need 'em.
Originally Posted By: HTSS_TR
I can't tell for sure, but maybe this is why vehicle manufacturers are specifying V rated tires on what appears to be generic 4 door sedans.
In N.A. we call that PYA - Protect Your A** - from liability!
I can't tell for sure, but maybe this is why vehicle manufacturers are specifying V rated tires on what appears to be generic 4 door sedans.
In N.A. we call that PYA - Protect Your A** - from liability!
CapriRacer, I know you're a tire expert of this forum. Your opinions are well regarded by me and many others. But I disagree with you on several points:
This is not a myth, what I said was my experiences with different speed rated tires on 1994 Lexus LS400. The car is capable to sustain up to 150 mph with V rated tires which is original equipment and recommended by Lexus.
With lower speed rated tires, to be able to drive at fairly high speed in desert heat, I increase the cold tire pressure to 34 PSI while the recommended is 30 PSI at So Cal ambient temperature at that time was 75-80F and ambient temperature at Death Valley was 115-125F, the max pressure on sidewall of that tire was 44 PSI. Cruise control was set at 85MPH and one in a while for passing traffic I sped up to 100-110 MPH without much drama. Yes, it did not feel as stable as with V rated tires but the car did not feel as it was about to fly off highway either. I believe tire manufacture built in some margin for speed rating, an S rated (113 MPH) can sustain 115-120 MPH for several hours without blowing up if it did not overloaded.
This combination is dangerous: tire with lower speed rate + lower pressure + overloaded and higher sustain speed with high ambient temperature.
Originally Posted By: CapriRacer
This must be the thread for myths. Here's another one:
Originally Posted By: HTSS_TR
.......
As long as I have the tires inflated few PSI above placard but below max pressure on side-wall, the car was safe to drive up to 100-110 MPH on trips to Vegas in summer, even with S rated tires.
.......
There are quite a few things that affect the speed capability of a tire.
1) Inflation pressure: John Baldwin published a study of the speed rating of tires at different inflation pressures and found that the lower the inflation pressure, the lower the speed capability. He adjusted the load according the the inflation pressure. He found as much as a 2 step drop in speed capability.
2) Heat: Tires are tested for speed rating in a room at 70°F. The tire only has to maintain the speed for 1 hour. Increases in ambient temperature reduce the speed capability. I can't remember who did the study, but it was found that temperatures that are experienced in the US desert Southwest (which would include Las Vegas) can adversely affect the speed capability by as much as 2 steps.
3) Age: John Baldwin also published a study on tire aging and found that 4 year old tires - even unused tires - has lost some speed capability - as much as 2 steps.
What I take from all of this is that there are circumstances where a tire could lose as much as 6 steps in speed capability(may be more!). Put another way, a V rated tire might only have an R capability (106 mph). I can't tell for sure, but maybe this is why vehicle manufacturers are specifying V rated tires on what appears to be generic 4 door sedans.
This is not a myth, what I said was my experiences with different speed rated tires on 1994 Lexus LS400. The car is capable to sustain up to 150 mph with V rated tires which is original equipment and recommended by Lexus.
With lower speed rated tires, to be able to drive at fairly high speed in desert heat, I increase the cold tire pressure to 34 PSI while the recommended is 30 PSI at So Cal ambient temperature at that time was 75-80F and ambient temperature at Death Valley was 115-125F, the max pressure on sidewall of that tire was 44 PSI. Cruise control was set at 85MPH and one in a while for passing traffic I sped up to 100-110 MPH without much drama. Yes, it did not feel as stable as with V rated tires but the car did not feel as it was about to fly off highway either. I believe tire manufacture built in some margin for speed rating, an S rated (113 MPH) can sustain 115-120 MPH for several hours without blowing up if it did not overloaded.
This combination is dangerous: tire with lower speed rate + lower pressure + overloaded and higher sustain speed with high ambient temperature.
Originally Posted By: CapriRacer
This must be the thread for myths. Here's another one:
Originally Posted By: HTSS_TR
.......
As long as I have the tires inflated few PSI above placard but below max pressure on side-wall, the car was safe to drive up to 100-110 MPH on trips to Vegas in summer, even with S rated tires.
.......
There are quite a few things that affect the speed capability of a tire.
1) Inflation pressure: John Baldwin published a study of the speed rating of tires at different inflation pressures and found that the lower the inflation pressure, the lower the speed capability. He adjusted the load according the the inflation pressure. He found as much as a 2 step drop in speed capability.
2) Heat: Tires are tested for speed rating in a room at 70°F. The tire only has to maintain the speed for 1 hour. Increases in ambient temperature reduce the speed capability. I can't remember who did the study, but it was found that temperatures that are experienced in the US desert Southwest (which would include Las Vegas) can adversely affect the speed capability by as much as 2 steps.
3) Age: John Baldwin also published a study on tire aging and found that 4 year old tires - even unused tires - has lost some speed capability - as much as 2 steps.
What I take from all of this is that there are circumstances where a tire could lose as much as 6 steps in speed capability(may be more!). Put another way, a V rated tire might only have an R capability (106 mph). I can't tell for sure, but maybe this is why vehicle manufacturers are specifying V rated tires on what appears to be generic 4 door sedans.
Originally Posted By: rationull
I'm not so quick to dismiss H rated tires as I am V rated. My Civic came with H rated tires, and while 130 sounds excessive (and I'll likely never take the car about 90 or so, even at a burst), from what I've heard, it's drag limited at around 120. I wouldn't be surprised if your Elantra was similar given that they have fairly similar power and weight numbers IIRC.
Rest assured I tested the hypothesis.
Of course, in a safe place.
I'm not so quick to dismiss H rated tires as I am V rated. My Civic came with H rated tires, and while 130 sounds excessive (and I'll likely never take the car about 90 or so, even at a burst), from what I've heard, it's drag limited at around 120. I wouldn't be surprised if your Elantra was similar given that they have fairly similar power and weight numbers IIRC.
Rest assured I tested the hypothesis.
Of course, in a safe place.
Originally Posted By: Quattro Pete
Like Capri mentioned, it is the auto makers that requested such tires.
My friends still with the manufacturers seem to have a different take on it.
The Explorer situation was classic underinflation.
It was no surprise to me that over 2/3 of the drivers who had blowouts were female.
Like Capri mentioned, it is the auto makers that requested such tires.
My friends still with the manufacturers seem to have a different take on it.
The Explorer situation was classic underinflation.
It was no surprise to me that over 2/3 of the drivers who had blowouts were female.
Originally Posted By: Volvohead
However, on many turbo 850s, the car can outrun an H speed rating. And on the recent R models, they specified Y speed/95 (XL) load rated tires - and they need 'em.
i can say without a doubt i have outrun the old Z rating of 146mph in my R without pushing the car at all, and mine is stock. the tires are Y rated and are XL. true the specific brand sucks, but i will not second guess Volvo on their reasoning for the higher load and speed rating.
o and this speed was achieved on a closed non times course, and not on public roads...
However, on many turbo 850s, the car can outrun an H speed rating. And on the recent R models, they specified Y speed/95 (XL) load rated tires - and they need 'em.
i can say without a doubt i have outrun the old Z rating of 146mph in my R without pushing the car at all, and mine is stock. the tires are Y rated and are XL. true the specific brand sucks, but i will not second guess Volvo on their reasoning for the higher load and speed rating.
o and this speed was achieved on a closed non times course, and not on public roads...
Last edited:
I think the only way our 850 NA could go faster than 130 is off a cliff
I ended up reserving the Goodyear Eagle GTs because it turns out they're on sale. This way it'll only be $40 more expensive (total) than the cheaper H rated ones I was quoted. For that price I'll take the peace of mind that comes with the spec'd V rating.
I ended up reserving the Goodyear Eagle GTs because it turns out they're on sale. This way it'll only be $40 more expensive (total) than the cheaper H rated ones I was quoted. For that price I'll take the peace of mind that comes with the spec'd V rating.
Originally Posted By: HTSS_TR
CapriRacer, I know you're a tire expert of this forum. Your opinions are well regarded by me and many others. But I disagree with you on several points:
This is not a myth, what I said was my experiences with different speed rated tires on 1994 Lexus LS400. The car is capable to sustain up to 150 mph with V rated tires which is original equipment and recommended by Lexus.
With lower speed rated tires, to be able to drive at fairly high speed in desert heat, I increase the cold tire pressure to 34 PSI while the recommended is 30 PSI at So Cal ambient temperature at that time was 75-80F and ambient temperature at Death Valley was 115-125F, the max pressure on sidewall of that tire was 44 PSI. Cruise control was set at 85MPH and one in a while for passing traffic I sped up to 100-110 MPH without much drama. Yes, it did not feel as stable as with V rated tires but the car did not feel as it was about to fly off highway either. I believe tire manufacture built in some margin for speed rating, an S rated (113 MPH) can sustain 115-120 MPH for several hours without blowing up if it did not overloaded.
This combination is dangerous: tire with lower speed rate + lower pressure + overloaded and higher sustain speed with high ambient temperature.
HTSS_TR,
Let me explain it this way:
This is all about risk.
There are 5 states that account for about 80% of the tire failures: AZ, CA, NV, TX and FL - pretty much in that order. A lot of this is population driven (meaning I would have expected other hot weather states to be in this mix, but I don't have enough information to do the statistics weighted by exposure. That is: the number of identical tires in the popluation)
Plus, these tire failures are almost exclusively on S and T rated tires.
Operating a tire at a lower load than the value on the sidewall and operating the tire at an increased tire pressure over the placard reduces the risk, but using tires with at least an H rating has an far. far greater effect.
As you point out, you haven't experienced a tire failure, but others have. The actual failure rates are low, but the consequences are pretty severe.
It is the severity of the consequences that is driving my statement. Clearly there are combinations where you will "not be a statistic", but there are things that can be done to greatly reduce the risk - like using a higher speed rated tire.
Put another way, if you operate your tires the way you described, there might be a 1 in 10,000 chance that you'll have a tire failure, but if you use an H rated tire the risk is virtually nil.
CapriRacer, I know you're a tire expert of this forum. Your opinions are well regarded by me and many others. But I disagree with you on several points:
This is not a myth, what I said was my experiences with different speed rated tires on 1994 Lexus LS400. The car is capable to sustain up to 150 mph with V rated tires which is original equipment and recommended by Lexus.
With lower speed rated tires, to be able to drive at fairly high speed in desert heat, I increase the cold tire pressure to 34 PSI while the recommended is 30 PSI at So Cal ambient temperature at that time was 75-80F and ambient temperature at Death Valley was 115-125F, the max pressure on sidewall of that tire was 44 PSI. Cruise control was set at 85MPH and one in a while for passing traffic I sped up to 100-110 MPH without much drama. Yes, it did not feel as stable as with V rated tires but the car did not feel as it was about to fly off highway either. I believe tire manufacture built in some margin for speed rating, an S rated (113 MPH) can sustain 115-120 MPH for several hours without blowing up if it did not overloaded.
This combination is dangerous: tire with lower speed rate + lower pressure + overloaded and higher sustain speed with high ambient temperature.
HTSS_TR,
Let me explain it this way:
This is all about risk.
There are 5 states that account for about 80% of the tire failures: AZ, CA, NV, TX and FL - pretty much in that order. A lot of this is population driven (meaning I would have expected other hot weather states to be in this mix, but I don't have enough information to do the statistics weighted by exposure. That is: the number of identical tires in the popluation)
Plus, these tire failures are almost exclusively on S and T rated tires.
Operating a tire at a lower load than the value on the sidewall and operating the tire at an increased tire pressure over the placard reduces the risk, but using tires with at least an H rating has an far. far greater effect.
As you point out, you haven't experienced a tire failure, but others have. The actual failure rates are low, but the consequences are pretty severe.
It is the severity of the consequences that is driving my statement. Clearly there are combinations where you will "not be a statistic", but there are things that can be done to greatly reduce the risk - like using a higher speed rated tire.
Put another way, if you operate your tires the way you described, there might be a 1 in 10,000 chance that you'll have a tire failure, but if you use an H rated tire the risk is virtually nil.
If you really wanted to save lives, you would forget the speed rating [censored] and go with traction rated tires.
- Status
