You will not find a tire for your RV90 with E Kennung. The tire 6.7-10 4PR/50F tt Rectangle RE is "erstausrustung"der RV90 end therefore you can always use them. Beacause there is no matching alternative with the same specifications available in the market.
The productiondate is unknown, but it is the original Bridgestone coming from the land of the rising sun.
For me it is also a gamble. I put all my savings in it
It will probably be the last chance to find the original tires from Bridgestone for our RV90 bikes.