Assuming you have access to Installer, you can read them in a separate application. This is called PDFviewer, as is available for download from installer. It can read PDF files on the phone, and those PDFs can be placed on the phone through SSH. For instructions on how to use SSH, read through here.
Install a Free app called Quickoffice Connect. If the PDF is small enough to email to yourself do so then click on the PDF attachment. You will be asked if you want to open in Connect chose yes. this will open the PDF in Quickoffice Connect. You can then view the PDF on your iPhone. If you close the program you can reopen and create a new folder. Open the email folder select the PDF and move it to your new folder. It also works with Docx and Xlsx,
Not exactly. Threads like this get bumped by spammers every couple of years with yet another fine solution (for money, of course) to the long-since-solved-for-free issue of getting a PDF on your iPhone. Then those posts get deleted, leaving anybody who replied looking like a fool
(the possible answers, of course, are now endless: iBooks, or Adobe Reader, or Dropbox, etc...)