From the DuPont website...
This unique balance of properties, which cannot be found in any other material, makes Tyvek® lightweight yet strong; vapor-permeable, yet water-, chemical-, puncture-, tear- and abrasion-resistant. Tyvek® is also low-linting, smooth and opaque
Tyvek is "vapor permeable"...it does breathe...further..
Because Tyvek® is water resistant, yet breathable, it is ideal for car, boat and camper covers. The unique nonwoven structure of Tyvek® protects against acid rain and salt spray by holding out more water than cotton, polyester or cotton/polyester covers; however, because it is breathable, it also allows trapped moisture to escape, helping to prevent rot and mildew. What's more, because Tyvek® does not absorb water, it is significantly lighter than other covers -- even when wet. Tyvek® is a proven shield from the sun, blocking 98 percent of the sun's damaging ultraviolet (UV) rays, and it is specially engineered to keep out abrasive dirt and dust, so finishes are less likely to become dull or stained.
Frogg Toggs are made of Tyvek......Tyvek can be "spun" to make it wearble or soft...or harder etc