Bank Rakyat Indonesia has the highest Tier 1 ratio among the top 4 banks

It will remain so over the next 18 months.

According to Moody's, the top four Indonesian banks have high Tier 1 ratios, but BRI and Bank Central Asia have greater buffers against problem loans owing to their stronger profitability and higher adjusted loan-loss reserves. 

Here's more from Moody's:

Among the top four banks, BRI has the highest Tier 1 ratio. This, coupled with its strong capability to generate internal capital, should result in the bank’s Tier 1 ratio remaining high over the next 18 months.

Bank Mandiri’s Tier 1 ratio of 13.5% at end-June 2013 was lower than that of its three major domestic peers. In our view, Bank Mandiri’s Tier 1 ratio is modest, considering its strong growth aspirations and weaker credit quality.

However, the bank’s high profitability, which indicates its strong capacity to generate internal capital, offsets this weakness.

Despite an expectation of sustained strong loan growth of 18% in 2013, the top four banks should maintain their capital ratios at around the current levels, given their high capacity to generate internal capital. The state-owned banks can expect to receive financial support from the government in case of need.