* Transmission type: A manual transmission will have a different RPM than an automatic at the same speed. The 1999 LHS almost certainly had an automatic transmission. Even within automatic transmissions, different gear ratios will yield different RPMs.
* Tire size: Larger diameter tires will result in lower RPMs at a given speed, while smaller tires will result in higher RPMs. If the tires are not the original size specified by Chrysler, the RPM will be off.
* Gear Ratio (for automatic): Even with the same tire size, variations in the final drive ratio (part of the differential) can slightly alter RPM.
To find a close approximation, you'd need to:
1. Find the gear ratios: Look up the specific gear ratios for your LHS's transmission in a repair manual or online. This includes the final drive ratio.
2. Determine your tire size: Check the sidewall of your tire for the size (e.g., 215/65R15).
3. Calculate RPM: Use an online RPM calculator that takes into account these factors. Many such calculators are available through a simple web search.
Without this specific information, any RPM I give you would be a guess and potentially inaccurate.
