Tread wear vs. tire pressure?
12-01-2011, 02:32 PM
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Tread wear vs. tire pressure?
I just got my new wheels and tires put on ( 35x12.5 r15x8 ) bfg all terrains. On the ride home I noticed the tires felt over inflated, so when I got home I checked the tire pressure. 3 of the tires were at max recommended psi (35 psi) and another was 38 psi.
I did the "chalk test" and found that only the center treads were actually making contact with the pavement, I than processed to lower the front 2 tires to 29psi and the rear tires to 30 psi, I repeated the chalk test and found that "more" tread was making contact with with the pavement, but still not entirely.
Now because of the amount of sidewall I now have with 35 inch tire on a 15x8 inch rim ( which by the way is a half an inch thinner than bfg recommends for this tire ) I dont feel comfortable lowering the psi further. I can already feel a huge difference in the handling coming from a 33x12.5 r17 mud tire.
So I guess my questions are...
1. Can I or should I lower the psi further until all treads meet pavement?
2. Can my treads ever meet the pavement correctly on a safe to drive psi on a 8 inch wide wheel?
3. ( stupid question ) can I loose a bead driving to fast on a turn if psi is a little too low? (highway speeds)
or any other recommendations would be greatly appreciated.
Thanks in advance!
Edit: forgot to mention that the measured psi was cold measured. ( not sure if it makes any difference )
I did the "chalk test" and found that only the center treads were actually making contact with the pavement, I than processed to lower the front 2 tires to 29psi and the rear tires to 30 psi, I repeated the chalk test and found that "more" tread was making contact with with the pavement, but still not entirely.
Now because of the amount of sidewall I now have with 35 inch tire on a 15x8 inch rim ( which by the way is a half an inch thinner than bfg recommends for this tire ) I dont feel comfortable lowering the psi further. I can already feel a huge difference in the handling coming from a 33x12.5 r17 mud tire.
So I guess my questions are...
1. Can I or should I lower the psi further until all treads meet pavement?
2. Can my treads ever meet the pavement correctly on a safe to drive psi on a 8 inch wide wheel?
3. ( stupid question ) can I loose a bead driving to fast on a turn if psi is a little too low? (highway speeds)
or any other recommendations would be greatly appreciated.
Thanks in advance!
Edit: forgot to mention that the measured psi was cold measured. ( not sure if it makes any difference )
Last edited by sam187st; 12-01-2011 at 02:45 PM.
12-01-2011, 03:43 PM
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im not running a/t's but im running km2's on a 15"x8" rim. I had to air all they way down to 21-22psi to get the full tread width to make contact with the road. The lower the tire psi the worse the mpg will be (because of how much tire is contacting) but the treadwear will be even across the tire. Over inflated will cause the middle of the tire to wear faster than the outside and the opposite with underinflation. So im keeping mine at the psi where the full tread touches the road. Of course ill push it to get the highest psi possible to help mpg but i want even wear.
12-01-2011, 04:09 PM
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im not running a/t's but im running km2's on a 15"x8" rim. I had to air all they way down to 21-22psi to get the full tread width to make contact with the road. The lower the tire psi the worse the mpg will be (because of how much tire is contacting) but the treadwear will be even across the tire. Over inflated will cause the middle of the tire to wear faster than the outside and the opposite with underinflation. So im keeping mine at the psi where the full tread touches the road. Of course ill push it to get the highest psi possible to help mpg but i want even wear.
