They are 7 and 7/8 inches according to my tape measure. I have pulled them off the rims in the picture. I don't want them. If you want them send me a PM and i'll send them to ya... FREE. I have to warn you, they are pretty hard and I don't have foams for them (not really necessary since they are hard) They will fit on T-Maxx rims, so I assume they will fit on Revo rims.
LMK