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Location: Removing a snake out of the neighbor's washing machine
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Quote:
Originally Posted by maduro lonsdale
To be fair, the extreme big wheel/baloney skin thing is starting to get some kickback from the enthusiast world, like Car & Driver. They often prefer slightly smaller wheels like 18s or 19s over available 20s or bigger.
The only ride I would appreciate some 19s or 20s on is a
Narrower wheels, regardless of diameter or tire profile, tend to roll straighter and resist every little crack or hole in the roads compared to wider wheel/tire combos, which tend to 'tram-line', or follow ruts or other surface imperfections.
Narrower wheels are worse then wide wheels. You get better traction and road handling with a wider wheel. A thin wheel will follow the ruts. Look at High performance cars like Porsche or a Corvette and see that the wheels are wider. They make them that way for a reason.
Location: Removing a snake out of the neighbor's washing machine
3,095 posts, read 2,040,022 times
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Quote:
Originally Posted by SOON2BNSURPRISE
Narrower wheels are worse then wide wheels. You get better traction and road handling with a wider wheel. A thin wheel will follow the ruts. Look at High performance cars like Porsche or a Corvette and see that the wheels are wider. They make them that way for a reason.
Completely backwards.
Take a 7" wide tire: 3.5" to either side of centerline.
Take a 10" wide tire: 5" to either side of center line. Much wider radius, and more likely to be tugged at by pock marks and cracks, and uneven pavement.
The wider tire in my example will be tugged easier to one side, IE, by a bump or crack 4" from the centerline where as the narrower tire might miss the imperfection entirely, and continue to track straight.
The narrower, higher profile tire will absorb the imperfection better and be tugged or bumped from straight ahead less readily, since more vehicle weight is concentrated over it.
The wider, lower profile tire excels only in two aspects of handling: Acceleration, and more responsive steering.
The cars you referenced are sports/performance cars, for high speeds and turning on a dime - not what the average 9 to 5er needs, or a family heading to church on the weekends.
Take a 7" wide tire: 3.5" to either side of centerline.
Take a 10" wide tire: 5" to either side of center line. Much wider radius, and more likely to be tugged at by pock marks and cracks, and uneven pavement.
The wider tire in my example will be tugged easier to one side, IE, by a bump or crack 4" from the centerline where as the narrower tire might miss the imperfection entirely, and continue to track straight.
The narrower, higher profile tire will absorb the imperfection better and be tugged or bumped from straight ahead less readily, since more vehicle weight is concentrated over it.
The wider, lower profile tire excels only in two aspects of handling: Acceleration, and more responsive steering.
The cars you referenced are sports/performance cars, for high speeds and turning on a dime - not what the average 9 to 5er needs, or a family heading to church on the weekends.
This.
Things aren't always as they seem. Attestation: I drove a 2013 Corvette Grand Sport (base V8 but with wider tires than the base model, a staggered set of 275/35-R18 in the front and 325/30-R19 in the rear).
You needed to drive this with BOTH HANDS. None of this "one-hand at 7:30 and the other on the shifter" cruising. The wheel would TUG when you hit the slightest imperfection. Part of this is due to the wide wheels, part of this is due to the toe and caster of these vehicles, which is not always so close to being zeroed out like economy cars.
Mercedes, for example, are a brand that has markedly positive caster - if you can imagine a grocery cart's wheels as they appear when rolling backward, but locked this way and you're traveling forward - it allows suspension to absorb input more directly and contributes to stability, especially at high speeds.
Things aren't always as they seem. Attestation: I drove a 2013 Corvette Grand Sport (base V8 but with wider tires than the base model, a staggered set of 275/35-R18 in the front and 325/30-R19 in the rear).
You needed to drive this with BOTH HANDS. None of this "one-hand at 7:30 and the other on the shifter" cruising. The wheel would TUG when you hit the slightest imperfection. Part of this is due to the wide wheels, part of this is due to the toe and caster of these vehicles, which is not always so close to being zeroed out like economy cars.
Mercedes, for example, are a brand that has markedly positive caster - if you can imagine a grocery cart's wheels as they appear when rolling backward, but locked this way and you're traveling forward - it allows suspension to absorb input more directly and contributes to stability, especially at high speeds.
Good points.
Caster, camber, toe all affect steering response, probably more so than simple tire width.
The wider, lower profile tire excels only in two aspects of handling: Acceleration, and more responsive steering.
So what you're saying is you prefer a vehicle that accelerates worse, has less braking (because the converse of acceleration is braking, actually acceleration on an opposing vector), and doesn't steer as well.
And this is a bad thing how?
What could possibly go wrong driving a car that has less traction in all aspects of its driving envelope?
Location: Removing a snake out of the neighbor's washing machine
3,095 posts, read 2,040,022 times
Reputation: 2305
Quote:
Originally Posted by maduro lonsdale
Good points.
Caster, camber, toe all affect steering response, probably more so than simple tire width.
Yes, the interaction of all of those angles affect steering response, steering 'weight'/heft away from centered, and how quickly the steering wheel centers from a turn.
The primary centering forces are Caster angle and Kingpin angle(known in this century simply as SAI - steering axis inclination).
The more of each, in varying proportions, all other things equal, results in more stability straight ahead and more resistance to driver steering input. Varying degrees of power assist can reduce amount of driver effort to steer, particularly at lower(parking lot) speeds.
Knowing that wider wheel/tire combinations are more reactive to lateral forces, a manufacturer could do a number of things to offset this tendency:
1) Increase caster and/or SAI angle
2) Decrease amount of steering assist, esp. at higher speeds - or employ variable power assist, which reduces power steering progressiveky at increasingly higher speeds.
3) Any combination of the above, depending upon target audience and intended use of vehicle.
So, given the same exact vehicle, built for several years on narrow 70-series high profile tires, and now switching to, say, wider 50-series lower profiles, the engineers could:
Increase the stability alignment angles mentioned above from what they were with the narrowe tires, or, reduce the amount of power steering assist given the existing alignment angles used with the narrower tires(remember, a road imperfection can 'steer' a car's front wheels easier also if that car has wider wheels combined with higher steering assist!), or, a combination of more aggressive caster/SAI and reduced or variable power steering.
Last edited by TheGrandK-Man; 03-05-2019 at 05:48 PM..
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