Edited 29 DEC 20 for clarification - cannot attach the Excel sheet calculations
Being an engineer, I had to crunch the numbers for the negative effect on installing heavier tires has on vehicle acceleration. If you are considering upgrading your tires to something larger / heavier, it will have an effect on vehicle performance and decrease your fuel economy (assuming no retunes, re-gearing your differential, etc.).
In my case I compared the stock Duratrac tires that came with my 2018 Midnight edition Z71 to a larger LT tire. The calculation baseline is the constant torque at the rear axle required on the stock truck to accelerate it from 0 to 60 mph in 8 seconds. Then with the assumption of all else being equal (same constant rear axle torque), the larger and heavier 285/70/R17 tires results in a ~10% decrease to only accelerating to a speed of 55mph at the end of 8 seconds.
265/65/R17 Duratracs are 44 lbs each
285/70/R17 Tires at 55 lbs each (similar to a Toyo Open Country A/T III, LT load range C)
The issue here is the fact that while the weight per tire increases by 25%, the rotational inertia increases by 41.4% and more of the engine torque has to be used to accelerate the rotational velocity of the wheels. Further, for the same rear axle torque applied the larger diameter tire will decrease the resultant force at the tire contact patch with the road (longer lever arm). Also of note is that the calculations correlate to the rule of thumb that each extra pound of rotational weight is equivalent to 10 pounds of sprung weight (payload).
Thus, more energy / fuel is required to rotationally accelerate the heavier tires. Re-gearing your differentials will help (if you're willing to pay the $$$). This mpg loss will largely impact city type driving while constant speed highway driving is less affected. Other aerodynamic issues due to lifting the vehicle with larger / wider tires affect highway fuel economy greater.
If you're looking to get bigger tires, do your homework and figure out what you're willing to sacrifice before spending all that money. In my case since my truck is a daily driver doing largely city type conditions with occasional highway trips, my goal is to ultimately get the largest, lightest, yet toughest tire I can. Example, the BF Goodrich AT TA KO2 LT 285/70/R17 load range C are only 50.3 lbs. each.
References:
If you really want to understand the physics behind the phenomena here, look up rotational moment of inertia:
Being an engineer, I had to crunch the numbers for the negative effect on installing heavier tires has on vehicle acceleration. If you are considering upgrading your tires to something larger / heavier, it will have an effect on vehicle performance and decrease your fuel economy (assuming no retunes, re-gearing your differential, etc.).
In my case I compared the stock Duratrac tires that came with my 2018 Midnight edition Z71 to a larger LT tire. The calculation baseline is the constant torque at the rear axle required on the stock truck to accelerate it from 0 to 60 mph in 8 seconds. Then with the assumption of all else being equal (same constant rear axle torque), the larger and heavier 285/70/R17 tires results in a ~10% decrease to only accelerating to a speed of 55mph at the end of 8 seconds.
265/65/R17 Duratracs are 44 lbs each
285/70/R17 Tires at 55 lbs each (similar to a Toyo Open Country A/T III, LT load range C)
The issue here is the fact that while the weight per tire increases by 25%, the rotational inertia increases by 41.4% and more of the engine torque has to be used to accelerate the rotational velocity of the wheels. Further, for the same rear axle torque applied the larger diameter tire will decrease the resultant force at the tire contact patch with the road (longer lever arm). Also of note is that the calculations correlate to the rule of thumb that each extra pound of rotational weight is equivalent to 10 pounds of sprung weight (payload).
Thus, more energy / fuel is required to rotationally accelerate the heavier tires. Re-gearing your differentials will help (if you're willing to pay the $$$). This mpg loss will largely impact city type driving while constant speed highway driving is less affected. Other aerodynamic issues due to lifting the vehicle with larger / wider tires affect highway fuel economy greater.
If you're looking to get bigger tires, do your homework and figure out what you're willing to sacrifice before spending all that money. In my case since my truck is a daily driver doing largely city type conditions with occasional highway trips, my goal is to ultimately get the largest, lightest, yet toughest tire I can. Example, the BF Goodrich AT TA KO2 LT 285/70/R17 load range C are only 50.3 lbs. each.
References:
If you really want to understand the physics behind the phenomena here, look up rotational moment of inertia:
