noob, led resistor

Hi,all....first post,and its a real yawner for most of you,but I aint that bright....hence why I need the LED lights!So.... bought a pair of 24 LED (white) strips from e bay,12v,to go on my LandRover Discovery 1998 diesel.The seller has NO info on the items other than that they are 12 volt.They appear to be 3mm done LEDs in a series parallel set up encased in clear flexi plastic,with two wires hanging out.I would think they are in groups of three as thats the most you can do with whites (isnt it?),but not sure,may be 3v's in 4's....hard to tell. Anyway,what I dont know is the wattage to limit the current to.Not having any of the specs means I cant calculate myself.I reckoned a resistor of either 470 or 560 K ohm,but unsure of the amperage to use. I have old boards around that I salvage bits from and while I can use calculators to work out impedence I dont know how to decode the things as to amps,other than on wirewounds where its written ! The alternator will be putting out about 13 and a half or more. Any advice on this would help me to put these in as day-running lights on the sidelight circuit.

They are suited to 12V. You don't need resistors. That 12V should mean typical auto 12V - ie, up to 15V or more. LEDs really arn't that critical. Most design with 1.7V LEDs as if they are 2V LED else even ignore their voltage totally in calculations (for 12V and higher). Although the latter (ignoring their voltage) lowers their current (increased voltage drop required hence larger resistor), it has little effect - especially brightness. (Oops - we are talking current, not brightness, but LED currents have a reasonable variation and specs are conservative. Besides, 2V to 1.7V is like 14.1V to 12.0V - an most auto systems have a long-term max of 14.4V )    [ Please - any Nordics that read this and disagree, please shut the Fup unless you (1) understand the issue; (2) are prepared to discuss rationally, & (3) not bug out of discussions for personal reasons. ]   (I think tribal English comrades understand that...)