Hello, I have an 05 Cadillac STS V8. The car came with SL 235/50R17 tires. I just put all new tires on the vehicle in the OEM size except they are XL with a load index of 100. The vehicle weighs 4,000 lbs and with myself, passenger, and some tools etc I am probably driving around at ~4,500 lbs. The factory door sticker says to run the tires at 30 psi front and rear. The XL tires state they have maximum load capacity at a maximum pressure of 50 psi. Obviously the load capacity of these tires far exceeds the weight of my vehicle.
Is it safe to run these XL tires at the factory recommended 30 psi or do the XL tires require a higher psi to be safe? I have been asking around and getting mixed answers. The shop who installed the tires for me said to run them at 40 psi, another post I found online said to stick with the factory 30 psi regardless of load rating, and another source said to never run a tire more than 10% lower than the maximum pressure rating which in this case would be 50-5= 45 psi. I am currently running them at 36 psi and they look and feel fine.
My main concern, and reason behind getting new tires, was traction. The vehicle is RWD with 320 hp and with the amount of rain we get in north FL traction is very important. My old tires, despite looking fine, were simply old (about 4 years), hard, and one size too small (decision of previous owner). On wet roads, anything more than 1/4 throttle and the rear end was all over the place, traction control could not keep up. The new tires seemed to have fixed this issue completely. I bring this up as when choosing the psi to run, traction and safety is my biggest concern. I don't drive much, the tires will probably be replaced due to age not lack of tread. I keep up on maintenance, always check psi, rotate tires, etc. The car mostly sits Monday thru Friday but I do make the occasional trip from Jacksonville to West Palm, about 300 miles each way.
Any input is much appreciated.
Ryan K
Orange Park, FL
Is it safe to run these XL tires at the factory recommended 30 psi or do the XL tires require a higher psi to be safe? I have been asking around and getting mixed answers. The shop who installed the tires for me said to run them at 40 psi, another post I found online said to stick with the factory 30 psi regardless of load rating, and another source said to never run a tire more than 10% lower than the maximum pressure rating which in this case would be 50-5= 45 psi. I am currently running them at 36 psi and they look and feel fine.
My main concern, and reason behind getting new tires, was traction. The vehicle is RWD with 320 hp and with the amount of rain we get in north FL traction is very important. My old tires, despite looking fine, were simply old (about 4 years), hard, and one size too small (decision of previous owner). On wet roads, anything more than 1/4 throttle and the rear end was all over the place, traction control could not keep up. The new tires seemed to have fixed this issue completely. I bring this up as when choosing the psi to run, traction and safety is my biggest concern. I don't drive much, the tires will probably be replaced due to age not lack of tread. I keep up on maintenance, always check psi, rotate tires, etc. The car mostly sits Monday thru Friday but I do make the occasional trip from Jacksonville to West Palm, about 300 miles each way.
Any input is much appreciated.
Ryan K
Orange Park, FL