Tiff is one of the most high quality Image formats.
The problem with high quality image formats if three-fold.
1. The files are much bigger than normal JPG or PNG images (you may have discovered this already). The size of these images will cause the website to load slowly, as the increased file size can take extra time to download,
2. The browser may have a harder job redering the image, as it will have a large amount of data to render.
3. Not all computers/browsers can view these images in a web-page1, so not everyone could see them.
For these reasons we use PNG or JPG images, as they are much smaller in file-size, and can be of reasonable image quality. (PNG rather that JPG for better quality).
So convert TIFF images into PNG or JPG images, which will mean that almost all browsers will show the images, and people will get a fast dowload making your website appear fast and responsive..
Browser Image format support http://en.wikipedia.org/wiki/Comparison_of_web_browsers#Image_format_support