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Old 01-29-2020, 04:46 PM   #1
RidingOnRailz
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Cool Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

What would be the Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle? Tires are same size, of course.

Cannot find information about this anywhere online!

Thanks in advance.
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Old 01-30-2020, 07:30 AM   #2
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Re: Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

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Originally Posted by RidingOnRailz View Post
What would be the Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle? Tires are same size, of course.

Cannot find information about this anywhere online!

Thanks in advance.
Because of the wide range, it can not be predicted. That's why the rules say not to do that. The tires should be as close to the same as possible.

Ya' see, in emergency maneuvers, cars tend to rotate around the odd tire - and the more odd the tire is, the stronger that tendency.

Further, the same applies to the front/rear. The more different, the more likely the vehicle will swap ends in emergency situations.

So the ideal set up is to have 4 of the same make and model tire with the same amount of wear.
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Old 01-30-2020, 07:05 PM   #3
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Re: Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

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Originally Posted by CapriRacer View Post
Because of the wide range, it can not be predicted.
That's why the rules say not to do that.
The tires should be as close to the same as possible.

Ya' see, in emergency maneuvers, cars tend to rotate around
the odd tire - and the more odd the tire is, the stronger that
tendency.

Further, the same applies to the front/rear. The more different,
the more likely the vehicle will swap ends in emergency
situations.

So the ideal set up is to have 4 of the same make and model
tire with the same amount of wear.

Thanks. Confirms what I already knew. Just wanted to learn more of the effects of mismatched load ratings on same axles, handling dynamics, etc.

This particular vehicle specifies, on its B-pillar inflation decal, 93V-rated tires. Only one such tire is - the front passenger side. The others are a variety of 94T and 94V. The rears exhibit moderate dry-rot and cracking, and the fronts are of the same make, but different models and categories!

When running the vehicle through Tire Rack for OEM suggestions, I got back no 93V tires, only 94V, across a range of categories(All Season, Grand Touring All Season, etc.).

Do they even make 93V anymore in the OEM size for my car?
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Old 01-31-2020, 08:45 AM   #4
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Re: Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

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Do they even make 93V anymore in the OEM size for my car?
First, for the same tire size dimensions (that is, the numbers), the difference of a single load index (in this case, the difference between a 93 and a 94) is an artifact of the way different tire standardizing organizations set up their standards.

Put another way, the tires aren't different in any significant way aside from the make/model. So buy the 94V's with confidence.
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Old 01-31-2020, 09:47 AM   #5
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Re: Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

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Originally Posted by CapriRacer View Post
First, for the same tire size dimensions (that is,
the numbers), the difference of a single load
index (in this case, the difference between a 93
and a 94) is an artifact of the way different tire
standardizing organizations set up their standards.

Put another way, the tires aren't different in any
significant way aside from the make/model. So
buy the 94V's with confidence.

Ok. And do higher load ratings, and for that matter, higher speed ratings, mean stiffer tire sidewalls?
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Old 02-01-2020, 08:01 AM   #6
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Re: Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

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Ok. And do higher load ratings, and for that matter, higher speed ratings, mean stiffer tire sidewalls?
First, THEE most contributor to sidewall stiffness is inflation pressure. You get a much harsher ride when you add inflation pressure than you get between load ratings of the same make/model tire.

Plus. load ratings and speed ratings aren't necessarily tied to sidewall stiffness - BUT - higher speed ratings TEND towards stiffer sidewalls in order to get better handling (quicker response.), but not always, and there are so many exceptions, it's almost wrong to say what I just said.

Load ratings are a bit more difficult to explain. If we are talking about passenger car tires, sidewall stiffness (that is ride harshness) varies more between makes and models, than between Standard Load (SL) and Extra Load (XL) - and as I explained above, the difference of a single digit load index in the same size is not really a difference.

But in LT tires (ones that use Load Range), within a given make and model, a higher load range will have a stiffer sidewall - BUT - that stiffness will be over shadowed by the inflation pressure.

Put another way, if I operate a Load Range C tire at 50 psi, it will ride harsher than the same make and model tire in a Load Range E at 40 psi.
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Old 02-01-2020, 08:55 AM   #7
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Cool Re: Effect On Handling of Tires With Different Speed AND Load Ratings on SAME Axle?

Quote:
Originally Posted by CapriRacer View Post
First, THEE most contributor to sidewall stiffness is
inflation pressure. You get a much harsher ride when you
add inflation pressure than you get between load ratings of
the same make/model tire.

Plus. load ratings and speed ratings aren't necessarily tied
to sidewall stiffness - BUT - higher speed ratings TEND towards
stiffer sidewalls in order to get better handling (quicker
response.), but not always, and there are so many exceptions,
it's almost wrong to say what I just said.

Load ratings are a bit more difficult to explain. If we are talking
about passenger car tires, sidewall stiffness (that is ride harshness)
varies more between makes and models, than between Standard
Load (SL) and Extra Load (XL) - and as I explained above, the
difference of a single digit load index in the same size is not really
a difference.

But in LT tires (ones that use Load Range), within a given make
and model, a higher load range will have a stiffer sidewall - BUT -
that stiffness will be over shadowed by the inflation pressure.

Put another way, if I operate a Load Range C tire at 50 psi, it will
ride harsher than the same make and model tire in a Load Range
E at 40 psi.

What an education! Thanks!

As far as the 93V thing goes, the tire decal on my Accord does specify that load & speed, yet now, ten years after its assembly, that combo seems scarcer than hens teeth - at least in the size tire this Accord requires. I'm a stickler for specs, Capri, that's why I pushed that point. But given what you said, I guess I can deal with 94V, especially if I routinely haul bagsa cement, ay'know whadd I mean?

So your suggestion is, watch those pressures. And that I do, weekly, let alone monthly.

An anecdote:
Over a decade of helping out family, friends, and colleagues with their vehicle's tire pressures, I have noticed the following pattern:

45% of folks tires are overinflated, 45% are underinflated, and about 10% are anywhere near OEM or specified cold pressure!

Most of those that do regularly check, at least once per month, are of the school that 'higher pressure is better'. Many even run the Max Cold numbers on their vehicles, or, at least 5psi over what is specified on their vehicle's load and tire placards. You pretty much know whose car we all pile into for long trips - and it's not one of those!

Those that don't check, or even know what a gauge looks like, their tires are all over the map: One tire, spot on. The other, waaaay overinflated, and the remainder, somewhere around 20-25psi. smh.. And they're complaining about having a hard time controlling their car, or thinking it needs aligning, etc.

Then I come along, do what I have to do, and to them, it's like I put all new tires & suspension parts on the thing! smh They never realized that their vehicle could actually handle! And we're not talking Mazzos and Beemers here, just every day whips.

Capri: How do we pull vehicle operators in from the two inflation extremes?

Everyone would enjoy driving more, be less grouchy and road-rageous, and help the planet also!

Last edited by RidingOnRailz; 02-01-2020 at 11:50 AM.
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