no antenna comes set from the factory. The mounting location of the antenna/ ground plane/length of feed wire/type of mount all play a role in the swr. So you and I could have the same truck, same antenna but I put it on the roof and you mount it on the bumper. My SWR should be close to 1:1 (but no way to know) and yours could be ok or horrible, still no way to tell without an swr meter. If your swr is 1:3 you would work ok, but your signal would be weaker and you will put stress on the transmitter. Any more than 1:3 and you will blow up the transmitter.
Oh and all antennas are adjustable. You lengthen them by cutting the cover off slightly and uncoiling, or shorten by cutting a little bit off at a time until you get the desired swr.