Tires/Wheels – Increase Width (grip) vs. More Weight (rotating mass)?
12-10-2011, 11:34 AM
#1
Drifting
Thread Starter
Tires/Wheels – Increase Width (grip) vs. More Weight (rotating mass)?
At the IMIS event at Indy this week-end I had a long talk with a senior engineer at Hoosier Tire, and also visited with several wheel manufacturers. My main concern was to learn as much as I could to help choosing the ideal wheel and tire combo.
In summary the advice was “bigger is not always better”, and “there is point of diminishing return as size increases”. However, to quantify it to a precise solution for my application would have to consider dozens of other variables, both for my set-up and the specific tires and wheels.
The most obvious advantages of increased tire/wheel width is the increased area of the contact patch, and improved grip on acceleration, braking and cornering.
The primary downside of the increased tire/wheel width is the additional weight of the rotating mass, which the consensus of the experts I talked to was a 4:1 ratio. A 5 lb. increase on each corner for a larger tire/wheel would be an effective weight of 20 lbs per corner, or 80 lbs. heavier for the car.
Of course, other variables would include the moment of inertia, distortion of the contact patch, the slip angle, aspect ratio, car weight and suspension set-up, track conditions, and the specific weight dispersion of the tire/wheel selection.
I would like some input from the track gurus on the forum. Ideally, I would like feedback based on actual data analysis. Track experience and “seat of the pants” observations are also welcome, but they tend to be pretty subjective.
The scenario: Is the benefit of a 1” wider wheel/tire greater than the disadvantage of the additional weight of the resulting rotating mass? If so, is the benefit significant, or just a marginal improvement?
Thanks all.
In summary the advice was “bigger is not always better”, and “there is point of diminishing return as size increases”. However, to quantify it to a precise solution for my application would have to consider dozens of other variables, both for my set-up and the specific tires and wheels.
The most obvious advantages of increased tire/wheel width is the increased area of the contact patch, and improved grip on acceleration, braking and cornering.
The primary downside of the increased tire/wheel width is the additional weight of the rotating mass, which the consensus of the experts I talked to was a 4:1 ratio. A 5 lb. increase on each corner for a larger tire/wheel would be an effective weight of 20 lbs per corner, or 80 lbs. heavier for the car.
Of course, other variables would include the moment of inertia, distortion of the contact patch, the slip angle, aspect ratio, car weight and suspension set-up, track conditions, and the specific weight dispersion of the tire/wheel selection.
I would like some input from the track gurus on the forum. Ideally, I would like feedback based on actual data analysis. Track experience and “seat of the pants” observations are also welcome, but they tend to be pretty subjective.
The scenario: Is the benefit of a 1” wider wheel/tire greater than the disadvantage of the additional weight of the resulting rotating mass? If so, is the benefit significant, or just a marginal improvement?
Thanks all.
12-10-2011, 11:50 AM
#2
Team Owner
Member Since: Jun 1999
Location: Miami bound
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You're going to get 5 pages of "it depends." Car, track, driver and length of race vs TT/qualifying all play huge roles. What works at RdAtl might not at Mid-O and vice-versa. Do you want fast for a 20lap average or 1 hand grenade lap? Better balanced cars might able to get away with smaller tires for longer. So many variables there is no rule of thumb. Te$t te$t te$t and see what works for you and your car. F1 teams entered last season on a new tire and until they put it on track and studied the data they had no idea what was going to happen. Neither do we.
12-10-2011, 12:45 PM
#3
Melting Slicks
I would love to try the new Michelin slick in 37/71-18 size; 14.8" tread width on a 14.5" wheel, 15.7" section width.
It's for LMP1/2 cars...... can't believe the size of that tire!
It's for LMP1/2 cars...... can't believe the size of that tire!
12-10-2011, 10:35 PM
#5
12-11-2011, 02:53 PM
#6
Melting Slicks
Aside from how interesting and impressive that huge tire is, there was a reason I posted about it; what may be considered too much tire for one car is not enough for another. Horsepower, weight, mechanical grip, aero grip (especially) all combine to determine an optimal wheel/tire for a given car (let alone the type of track one is on).
I follow ALMS and racing in general pretty closely but I did not realize the P1 and P2 cars were using tires that large (33 on the front and 37 on the rear), but on a car with that much HP and that much potential grip it would almost be impossible to have too much wheel/tire. The rest of us land somewhere else on the continuum, and as many of us have recently said, optimizing the wheel/tire combo for you car should be priority one over pretty much everything else (IMO).
I follow ALMS and racing in general pretty closely but I did not realize the P1 and P2 cars were using tires that large (33 on the front and 37 on the rear), but on a car with that much HP and that much potential grip it would almost be impossible to have too much wheel/tire. The rest of us land somewhere else on the continuum, and as many of us have recently said, optimizing the wheel/tire combo for you car should be priority one over pretty much everything else (IMO).
