RPO Codes

[77 Scottsdale]

Hello Chevy truck people, on my RPO sheet there are 3 codes that I cant find anywhere and I don't understand what they mean. the codes are ZLB, XLB, and YLB. they all say"L78-15/B TBLS HWY BL" Thanks for your help!

[Ronno6]

They appear to be tire codes:
http://cadillacfaq.com/rpo/rpo4.php?rpo=AG1%2CAG2%2CAJ1%2CAL1%2CAL0%2CAR9%2CASF%2CAT8%2CAU0%2CAU3%2CAXK%2CA31%2CBZY%2CB30%2CB32%2CB33%2CCF5%2CC60%2CDE6%2CDF5%2CEB1%2CEF7%2CEVA%2CE55%2CFE9%2CGGU%2CGME%2CG93%2CG94%2CHC4%2CJB9%2CJJA%2CKA1%2CKG7%2CK05%2CK18%2CK34%2CLLR%2CM30%2CNP5%2CNR6%2CNT7%2CNZZ%2CN33%2COAR%2CPUB%2CP2R%2CQA7%2CQLB%2CR9N%2CSLA%2CSLM%2CTL4%2CT61%2CT96%2CT98%2CUA6%2CUE1%2CUM8%2CUPF%2CUQA%2CUVC%2CUY7%2CU2K%2CVH9%2CVK3%2CVR4%2CVT7%2CV8D%2CXLB%2CYC3%2CYD3%2CYD5%2CYD6%2CYLB%2CZLB%2CZM6%2CZY1%2CZ82%2C1SC%2C1SZ%2C191%2C193&submit=SUBMIT

This is from a Cadillac site, but listed as the official GM RPO Database.

[77 Scottsdale]

Huh, its for the tire size. Thank you for that. it says the tires are supposed to be 285/75R16 that looks like a pretty big tire. No wonder my speedometer is like 6 mph off

[Big Chip]

Huh, its for the tire size. Thank you for that. it says the tires are supposed to be 285/75R16 that looks like a pretty big tire. No wonder my speedometer is like 6 mph off

Where does it say that?  It’s a K10, right?


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