I've encountered more times than I care to remember that idea from supposed tire professionals that if you have one pair of tires that has much deeper tread that the other pair, that the better pair belongs in the rear. This is dangerously misguided advice, and I'd like to explain why.
The thinking that underpins the myth is the idea that oversteer is safer than understeer, so you want more traction in the rear. But there are many reasons that putting your best tires in the rear is actually more dangerous.
DRY Traction
Most vehicles are front wheel drive. Because front wheel drive vehicles use the front tires to do all of the acceleration, most of the steering and most of the braking (due to weight transfer) , FWD vehicles wear the tires much faster up front.
SO we encounter the first flaw in the myth of best-tires-on-the-rear: you want your best tires in the position where they can contribute the most to the total vehicle traction. CLEARLY that is up front for a front drive vehicle. For AWD and RWD vehicles, it's still true because braking traction matters many times more for safety than does acceleration traction.
A modern vehicle with front weight bias and front drive will have much shorter braking distances, better cornering traction, and better accelerating traction if the tires with the best traction are up FRONT where they can contribute the most.
WET Traction
You especially want your fresher tires up front in wet conditions where hydroplaning is a risk. Hydroplaning is primarily a straight-line highway traction risk. The rear tires are following the fronts. Which means the water load on the rear tires is the remnant of what the fronts leave behind. Having good tires in the rear makes hydroplaning more likely when a loss of steering control results from the front tires hydroplaning.
If only the rear hydroplanes, a FWD car is self-correcting because the front is pulling the rear back into line. If the rear hydroplanes in a rwd or AWD vehicle, you can correct any trajectory deviation because you still have steering authority.
Hydroplaning up front is entirely uncorrectable. If your front tires lose traction and change the vehicle's trajectory, the driver has no steering authority to correct whatsoever. The additional traction in the rear is entirely wasted.
Winter Traction
In snow and ice, you need all of the wet traction advantages of having best tires up front-- steering traction primarily. But you also need the better tires up front primarily for braking (as you have a front weight bias and more ground contact pressure), and for acceleration on slick roads. If you lose cornering traction on snow or ice, oversteer is easily corrected. Understeer renders the car a ballistic projectile immune to control inputs.
Conclusion
The tire industry says the best tires go on the rear because some ignorant lawyers who don't know physics came up with that idea. They probably saw some data and misinterpreted it. The probably saw data showing the overcorrection/oversteer and loss of control was cited in a majority of accidents and decided that making the driver LESS empowered was the solution, thereby increasing the total number of accidents while altering the proportion of them due to oversteer/overcorrection.
This is poor reasoning. Obviously we want FEWER accidents and we want losses of traction to be correctible. The solution isn't making the driver into a helpless passenger on an understeering ballistic projectile, but rather to allow the the driver to correct the the vehicle's loss of traction within overall higher traction limits. This of course comes with the possibility that bad drivers will overcorrect. But they may not have had to correct at all if not for the loss of control resulting from less total traction.
EVERY race car is tuned to slightly favor steady state oversteer because oversteer gives a larger total performance envelope. The same logic applies even more so to the street where full throttle acceleration traction is not important and maximim braking and steering traction is even more critical as a contribution to the whole.
Your best tires belong up front in every street car in all weather in every driveline-RWD, FWD, AWD; summer, winter, spring, fall.
The thinking that underpins the myth is the idea that oversteer is safer than understeer, so you want more traction in the rear. But there are many reasons that putting your best tires in the rear is actually more dangerous.
DRY Traction
Most vehicles are front wheel drive. Because front wheel drive vehicles use the front tires to do all of the acceleration, most of the steering and most of the braking (due to weight transfer) , FWD vehicles wear the tires much faster up front.
SO we encounter the first flaw in the myth of best-tires-on-the-rear: you want your best tires in the position where they can contribute the most to the total vehicle traction. CLEARLY that is up front for a front drive vehicle. For AWD and RWD vehicles, it's still true because braking traction matters many times more for safety than does acceleration traction.
A modern vehicle with front weight bias and front drive will have much shorter braking distances, better cornering traction, and better accelerating traction if the tires with the best traction are up FRONT where they can contribute the most.
WET Traction
You especially want your fresher tires up front in wet conditions where hydroplaning is a risk. Hydroplaning is primarily a straight-line highway traction risk. The rear tires are following the fronts. Which means the water load on the rear tires is the remnant of what the fronts leave behind. Having good tires in the rear makes hydroplaning more likely when a loss of steering control results from the front tires hydroplaning.
If only the rear hydroplanes, a FWD car is self-correcting because the front is pulling the rear back into line. If the rear hydroplanes in a rwd or AWD vehicle, you can correct any trajectory deviation because you still have steering authority.
Hydroplaning up front is entirely uncorrectable. If your front tires lose traction and change the vehicle's trajectory, the driver has no steering authority to correct whatsoever. The additional traction in the rear is entirely wasted.
Winter Traction
In snow and ice, you need all of the wet traction advantages of having best tires up front-- steering traction primarily. But you also need the better tires up front primarily for braking (as you have a front weight bias and more ground contact pressure), and for acceleration on slick roads. If you lose cornering traction on snow or ice, oversteer is easily corrected. Understeer renders the car a ballistic projectile immune to control inputs.
Conclusion
The tire industry says the best tires go on the rear because some ignorant lawyers who don't know physics came up with that idea. They probably saw some data and misinterpreted it. The probably saw data showing the overcorrection/oversteer and loss of control was cited in a majority of accidents and decided that making the driver LESS empowered was the solution, thereby increasing the total number of accidents while altering the proportion of them due to oversteer/overcorrection.
This is poor reasoning. Obviously we want FEWER accidents and we want losses of traction to be correctible. The solution isn't making the driver into a helpless passenger on an understeering ballistic projectile, but rather to allow the the driver to correct the the vehicle's loss of traction within overall higher traction limits. This of course comes with the possibility that bad drivers will overcorrect. But they may not have had to correct at all if not for the loss of control resulting from less total traction.
EVERY race car is tuned to slightly favor steady state oversteer because oversteer gives a larger total performance envelope. The same logic applies even more so to the street where full throttle acceleration traction is not important and maximim braking and steering traction is even more critical as a contribution to the whole.
Your best tires belong up front in every street car in all weather in every driveline-RWD, FWD, AWD; summer, winter, spring, fall.
