Wednesday, Dec 28, 2016 at 21:55
" Manufacturers only care about ride comfort, not tyre durability! "
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I have heard that argument more times than I could possibly remember. I have never heard such BS.
For every k those TG s of
mine did on unsealed roads, they did at least ten on highways and freeways at those same pressures. They did not overheat or crack the sidewalls or wear the outer edges due to under inflation. I changed them because of age. They still had a few ks left in them.
I know Cooper, and maybe a few others, do recommend reducing pressures but Coooper do not make a 205 x 16 or a 7.50 x 16 LT. The TGs only come in those sizes. They are commercial tyres that are used all over the Outback and rural areas with the 7.50 being the most common. The 697 LT that I currently have are the same specifications and work at the same pressures.
I have worked for long enough in the motor industry in rural areas of NSW to know that local people don't get out and fiddle around changing pressures every time they go from sealed to unsealed roads.
Goodyear also told me the weight that each 1 psi increase in the rear tyres would support. That made it easy for me to adjust the rear pressures according to the load.
The other issue with pressures is the handling characteristics of the car. Tyres distort in corners resulting in them no longer pointing in the same direction as the wheels. That is called the slip angle. There is a certain ratio between the front and rear slip angles. The front is almost always higher than the rear. This determines whether the car understeers or oversteers. Just about every car is set up to understeer because very few drivers can handle oversteer
When my car is correctly loaded, the weight on the front wheels should not change. That is why only one front pressure is recommended. This leaves the slip angle constant.
The rear angle will increase as the car is loaded but the pressure should be increased accordingly. That will reduce the angle resulting in no change to the the front to rear angle ratio.
Changing tyre sizes and using your favorite pressures will change these vital angles and there will be a fair chance that it will not be for the better. Unfortunately if you have created any adverse effects, you most likely won't find out until it is too late.
Study the design of cars and don't worry about claims that the manufacturers are only interested in smooth rides. There is far more to it than that.
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