Quote:
Originally Posted by gedward
Sorry to barge in on the thread but i just joined the forum and I do not yet have the priviledge to create a new thread.
Does anyone know why BMW does not include the 245/50 R17 tyre size as an option for the F10?
I have a 528 with 18" rims and 245/45 tyres. I wish to change down to 17" due to suffering a lot of tyre damage caused by bad road conditions were i live.
The 17" rims would allow a higher profile tyre and hence better cushioning effect.
BMW lists the 225/55 R17 as the only option.
I do not want to loose the traction quality of the 245s but nobody at the local BMW dealership can inform me why the 245/50 R17 is not listed.
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BMW could have several reasons for not specifying a 245 section with the 17" rims.
Could be as simple as the tyre just doesn't work as well in that size. They will be striking a ride/handling balance for the given stock sizes and the 225/55 could be the best compromise in a run-flat, to speed rating and load index necessary in a 17" for the F10. Doesn't matter what tyres are available (or not) in alternative sizes, if it doesn't fit the criteria.
I run a 245/45 R18 summer tyre and the 225/55 R17 as winter wheels on my 535i and there isn't really a marked difference in ride quality. I sense the 17" tyre is stiffer in the sidewalls and therefore loses some of the gain you'd expect in a 17" wheel/tyre combination. Some of it could be running in cooler temperatures, but don't think it is the complete picture.
I'm not sure you'll lose too much grip if you opt for the best 225/55 R17 tyre you can source. I'm surprised how well a winter 225 section works on the 535i. BTW, in the 245/50 R17 size, there doesn't appear to be many tyres to choose from here in the UK in run-flat specification. And not to the normal BMW load/speed ratings either. Do you have a better range to choose from if you do depart from BMW sizing?
HighlandPete