Are you talking about your local variation of Sanskrit pronunciation?
This is how the majority of the Indians attempt to pronounce it.
And no Indians will pronounce it as 'r'.
My main question was in reference to the historical pronunciation
As for the historical pronunciation. People are not quite clear.
IIRC in several sources I read it was reconstructed as 'ar' (sort of a rhotic vowel). Because, the Vriddhi and Guna forms for vocalic 'r' are 'ar' and 'aar' respectively. In a similar vein, the Pali equivalents of the Sanskrit words have 'a' in the place of vocalic 'r'.
This would explain why at Sandhi, vocalic 'r' grammatically mutates into 'ar (and the degradation of vocalic 'r' to 'a' in Pali)'. So it seems correct to consider it historically as a rhotic vowel, which at some point became /ri~ru/.
yo dharmaṁ paśyati, sa buddhaṁ paśyati
One who sees the Dharma, sees the Buddha śālistamba sūtra
na pudgalo na ca skandhā buddho jñānamanāsravam
sadāśāntiṁ vibhāvitvā gacchāmi śaraṇaṁ hyaham
Neither a person nor the aggregates, the Buddha, is knowledge free from [evil] outflows
Clearly perceiving [him] to be eternally serene, I go for refuge [in him] saddharma-laṅkāvatāra-sūtra