Quote:
Originally Posted by TN_3
I am in the process of researching replacement tires for the RFTs on my incoming X3, and noticed that the factory tires have a load rating of 102. Most of the tires I am looking at have a rating of 98. I looked through the X3 manual and didn't see a minimum load rating recommended by BMW. Anyone know if there is one?
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Where did you find a specification for the factory tires having a "load rating of 102". The standard 35i tires are 245/50R18's with a load rating of 100V (meaning 800kg load and max speed of 240 kph (149 mph).
Are you sure you're comparing tires of the same size?
I checked ratings of (30) different tires in the 245/50 size (all I could find that fit the X3 35i standard wheels) and every single one had a 100 load rating. the more expensive "summer only" tires usually carried a 100Y or 100W rating, while the least expensive versions were rated at 100H (same 800kg load, but max speed reduced to 210kph (130 mph). Every single tire carried a "100" load rating.
A fully loaded X3 (carrying 903 lbs of passengers and cargo) has a gross vehicle weight of 5136 lbs, with about 58% on the rear (most loaded) axle.
That means that each tire must carry a load of 1490 lbs. A modern tire must have a minimum load rating of at least "95" (690kg - 1521lbs) for a fully loaded X3. Any tire with a "98" rating (750kG - 1653 lbs) would provide a nice safety margin. All the above assumes that tire pressures are increased appropriately for the higher load.