Tire Aspect Ratios, High-vs-Low Profile, and Straight-line Stability

Tire Aspect Ratios, High-vs-Low Profile, and Straight-line Stability

Assumptions: Same brand & model of tire, same alignment settings on test vehicle, same level of power steering assist, same road test trajectory, same weather conditions, and of course, same driver. Vehicle's cold tire pressure is maintained, to within 1psi, of vehicle mfg placard on door pillar, with both sets of tires.

Differences: 4 High profile(70 series for example) tires are mounted and driven, then, 4 Low profile(50 series) tires are mounted and driven. Maintenance, to within 2% of each other's diameter for speedometer accuracy, is taken into consideration.

Given the assumptions proscribed in the first paragraph: With which set of tires, the high-profiles or the lo-profiles, will the test vehicle..

  1. Track truer in a straight-line?

  1. Respond quicker to steering inputs?

  2. Feel heavier when turning the steering wheel away from center?

  1. Return the steering wheel quicker to center from turns?

Reply to
thekmanrocks
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I would think that the low profile would fit all of the questions. Less sidewall = less flex.

Reply to
Paul in Houston TX

Yep. But add

Will ride worse. Will transmit more noise into the vehicle.

In order to keep the same diameter on the same rim size the low profile will be MUCH wider which can cause interference issues. So plan on going up at least one size.

Reply to
Steve W.

OK, here are my perceptions based upon what I've read and observed over the years:

  1. Straight line stability: Goes to the skinny, low profile tire because more weight is concentrated in a narrower patch.

  1. Response to steering inputs: The wide, low profile tire because patch is wider left to right.

  2. Weight build up when turning the wheel: Skinny low profile tire, for reasons stated in #1.

  1. Quicker return from turns: Skinny low profile for reasons stated in #1.

Think about why stability angles(caster, SAI/kingpin) in factory wheel alignment specs in cars have increased drastically over 30+ years: From practically zero to two degrees of caster in the 1970s, to between 4-6deg caster for modern mainstream vehicles. During anout the same time when 75-series tires began being replaced by 70-series, and 60-series, and 50 and 40-series(!)

Narrower, high-profile tires of the same overall inflated diameter track straighter with less caster or kingpin, and in my opinion, handle accordingly. And are better overall in snow and ice.

So what are low-profiles better for? Appearances! Less ugly sidewalls, and acres of chrome wheel bling! Wowww! Oh, and straightline acceleration - which is not a criteria I consider handling.

Reply to
thekmanrocks

(snip)

Ever do any twisty road racing or fast mountain driving? I was amazed at how much better cars handle with low profiles. They have less squirm and go where you point the steering wheel now, not where it was pointed last. They stick to the road and don't peel under the wheels as much. But for normal driving around Houston, I stick with high profiles. They are more squishy and less harsh. Can't get much over 25 mph here anyways.

Reply to
Paul in Houston TX

Paul in Houston Tx wrote: "Ever do any twisty road racing or fast mountain driving?"

Not a lot, but I do know that wider low profile respond more readily to steering input - and to road imperfections. Not so high-profile tires.

I want to feel resistsnce to turning, in the form of weight build-up in turns, and a steering wheel that snaps quickly back to center from a turn.

Need a lot more caster(or less power steering boost) with wide tires to accomplish that.

Reply to
thekmanrocks

Two weeks ago:

Traded in my 2013 Hyundai Sonata Ltd with 55 series 17"s for an Elantra with 65 series 15"s. Handling difference is NIGHT vs DAY! Elantra tracks straighter, heavier steering, better return from turns. I feel like I'm actually DRIVING again.

Keep your low-profile 17" and wider WAGON WHEELS, I'm sticking with something that HANDLES.

Reply to
thekmanrocks

Excellent!

Reply to
Paul in Houston TX

You forgot:

4 inch shorter wheelbase 500 lbs less weight Different rear suspension Basically a different car. Likely had an alignment done before you bought it too, compared to the bashed-into-curbs, no-maintenance thing you turned in. So of course it's going to handle differently. Next time try swapping wheels & tires ON THE SAME CAR.
Reply to
Sanity Clause

"Sanity Clause" wrote in news:nst31j$70t$1@dont- email.me:

yep I gaurenty all things the same, the wider low profile tires will handle better, ride rougher but handle better. KB

Reply to
Kevin Bottorff

Sanity Clause wrote: " Likely had an alignment done before you bought it too, compared to the bashed-into-curbs, no-maintenance thing you turned in. So of course it's going to handle differently. Next time try swapping wheels & tires ON THE SAME CAR. "

I understand the differences, Clause, but I neglected to mention:

The Sonata had THREE alignments done, zero worn or damaged parts anywhere on its suspension, plus all engine fluids were up to date. I examined the alignment specs myself snd made sure they weren't just 'in the green' but where in the green they should be, side to side.

Read up on "Sonata steering issues" - it will be a revelation for you. Lower profile tires were just a small element to the 2011-14 Sonata's straight line stability problems over

50mph. Even after having steering mode electronically set to a higher-driver-effort-required mode(Hard, Sport) it was still a two-hand white knuckle experience in that car for a significant percentage of drivers.

Finally, Enterprise car sales would never let a car out of their lot in "bashed up no maintenance condition".

Reply to
thekmanrocks

Kevin Bottorff wrote: "I gaurenty all things the same, the wider low profile tires will handle better, ride rougher but handle better. KB "

I speak from actual driving experience. The skinny little 14" rims in the Nissan Versa tracked straighter and tighter than 60 or

50 series tires I've driven in anything, let alone my Elantra.

Given same diameter, wider tires will be affected more by road imperfections that can pull them side to side, than narrow high-profiles. A car with wider, low-profiles needs either: less power steering assist built in, or, a lot more Caster or SAI angle built in to resist road irregularities, than does one riding on 'skinnier' wares.

Not to mention skinnier tires concentrate more weight on a longitudinal contact patch - that is, parallel to direction car travels in. Cars drive forward and backward, not sideways. You want a contact patch shaped accordingly.

Reply to
thekmanrocks

snipped-for-privacy@gmail.com wrote in news:334832c8-1b69-44ea-8d53-07d1c48f1f60 @googlegroups.com:

Soooo you went from a poorly designed suspension to a good one and then want to blame the wide tires, you are a fool. your perceptions are 180 degrees wrong. the wider tires handle better and DO NOT follow the road irregularits as much. aparently you have little experiance with both wide and narrow tires on the same cars. I have done lots over the years. the only time handleing is worse is in rain or snow, possibly loose gravel. KB

Reply to
Kevin Bottorff

You both need to read these articles:

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Reply to
Bill Vanek

Kevin Bottorff wrote: "from a poorly designed suspension to a good one and then want to blame the wide tires, you are a fool. your perceptions are 180 degrees wrong."

I know what I felt, and what I felt in the Nissan Versa Note and the Elantra was a level of stability and confidence lacking in the particular Sonata I drove for two months. It was a 2013 Sonata Limited with 55 series V-rated tires. I'm willing to admit the power steering in that car left loads to be desired. And my Sonata's caster was 3.9-4.0 degrees - spec is 4.4deg plus minus half defre. But I had neither the money nor inclination to experiment with higher profile rubber or massive reconstruction to add just another half degree casteron that car.

"the wider tires handle better and DO NOT follow the road irregularities as much."

You think I made that up - about the irregularities? It's on every good tire website I visited.

apparently you have little experiance with both wide and narrow tires on the same cars. I have done lots over the years. the only time handleing is worse is in rain or snow, possibly loose gravel. KB

Reply to
thekmanrocks

It sounds like you're saying the problem was with the car, not the tires.

Reply to
dsi1

dsi1:

It was a combination:

The 2011-14 Elantra electric MDPS(motor driven power steering) system utilized a small rubber/ plastic coupler between the driver and rack sides of the motor. While insisting the premature wear of this $3 part had "no effect on steering performance", Hyundai issued a TSB in 2014 authorizing replacement of the coupling under exisiting warranty.

Mine was a 2013 Sonata Ltd, with 55-17 tires. I suspect that some play had built up around that coupler, and, combined with low-barely-in-spec Caster, contributed to the nudging and tugging I felt in the steering wheel at higher speeds.

The Sonata GLS(more of a base) of that year had higher 60 or 65 series profile tires, and perhaps I wouldn't have felt those sensations I felt with the wider tire and wheel pkg.

Reply to
thekmanrocks

Perhaps - I guess we're never know.

Reply to
dsi1

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