XL Rated tyres are designed for heavy cars, rather than for carrying 'heavy loads' EG some vehicles designed to carry more than 5 people & some estate cars may have XL rated tyres fitted as standard.
an XL rated tyre will achieve its maximum load bearing capacity at a higher PSI than a 'normal' tyre
In other words, if you had 2 identical tyres, 1 was XL rated and one wasn't, the 'normal' rated tyre might achieve its 'optimum' load bearing performance at 'say' 35 PSI, whereas the XL rates tyre would achieve its 'optimum' load bearing performance (or identical performance as the normal tyre) at 45 PSI
So YES an XL tyre should be inflated to a higher PSI
If you inflated an XL rated tyre to the same PSI as a non XL tyre, then the XL tyre would actually have a lower load capacity than the non XL tyre
Found this;
"Extra Load tyres are designed to be used at higher pressures than normal tyres. They have the same maximum load capacity as a normal tyre with the same Load Index but achieve this at a higher pressure. Normal tyres are inflated to pressures between 2 bar and 2.5 bar. They reach the maximum load capacity as specified by the Load Index when inflated to 2.5 bar (35psi) Eg for a Load Index of 94 this is 670kg. Extra Load tyres can be inflated to pressures up to 2.9 bar (41psi) and actually have a lower load capacity at the same pressure as a normal tyre with the same Load Index. To get the 670kg load capacity for a Load Index of 94, an Extra Load tyre must be inflated to 2.9 bar. At 2.5bar it will only have a load capacity of 595kg.
