How strong is Tarble?

[SSJ2]

18 apparently said he had a strong ki.

 

[Classic Adamas]

<Freeza

 

[Captain Cadaver]

What implications we're given beyond him having been an embarrassment at birth are pretty vague. Him being said to be a strong Ki doesn't mean much when it'd be compared to the average Earthling. The most we're given is Abo and Kado saying he gave them some trouble, though that could be interpreted in many different ways such as constantly managing to escape before they could home in on him and he even made it apparent he was nothing to them in power. Both versions of the special even have Roshi volunteering to take on opponents stronger than him, and even if he were already making his Manly GAINZ, it was made apparent they hadn't gone full force in the FnF Arc.
There's honestly nothing to solidly place him even above Raditz. At best, I could maybe see him around the 8-10k range assuming he got in enough of a physical confrontation with the brothers to get a Zenkai or two, but probably nothing beyond that.