CHICAGO, June 3 (Reuters) - U.S. FOB Gulf corn and soybean basis offers were weaker for old-crop loadings after the close on Tuesday, tracking the softer tone in interior markets and quiet interest as customers turn to cheaper South American offerings, traders said.
* Wheat basis offers for both HRW and SRW were steady against a backdrop of lower futures, now trading at three-month lows ahead of harvest.
* Traders said weakening interior basis values for soybeans, with processors rolling their spot bids from July to August futures - which reflected about a 20-cent drop in the flat price - added to the bearish market tone. Decatur, Illinois, rolled its spot bid to 95 cents over August futures on Tuesday.
* Old-crop FOB Gulf soybean basis offers fell 5 cents, with June at 90 cents over and July at 85 cents over July futures. New-crop offers were unchanged with October quoted at 120 cents over amid steady Chinese interest, traders said.
* U.S. FOB offers for June remain about $35 to $45 a tonne above new-crop Brazilian and Argentine soybeans now coming to port.
* CBOT July soybeans ended 19-1/4 cents lower at $14.81-1/4 a bushel while November soy closed 8 down at $12.21-3/4.
* U.S. FOB Gulf corn values for old crop - July, August, September - fell 3 cents to 82 cents over futures, with inquiries slow given South American competition.
* Greenhouse-like conditions for the newly planted crop across the central Midwest cast a bearish sentiment over cash and futures, traders said. CBOT July corn closed at $4.58-1/4, down 7-1/4 cents.
* FOB SRW wheat values held at 70 over and 68 over CBOT July for first-half and second-half June, respectively, as traders let futures do the work of lowering prices. CBOT July wheat ended 8-1/4 lower at $6.12-1/2.
* U.S. SRW wheat is still seen about $10 a tonne cheaper than French wheat for June but Black Sea wheat is quoted about $5 per tonne cheaper than U.S. Gulf FOB values, traders said. Winter wheat harvest is just starting in the southern states, including the HRW crop in Texas and the SRW harvest in Mississippi and Louisiana. The harvest should pressure FOB and CIF values at the Texas and Louisiana Gulf over the next month.
* HRW track and FOB values stayed steady as futures in Kansas City July futures fell 11 cents to close at $7.07-3/4.
* Hard red wheat June offers were quoted at 143 cents over futures, while July was at 140 over - both unchanged from Monday.
(Reporting by Christine Stebbins; Editing by Ken Wills)