YannickVT

Hi all,

due to local road conditions I am planning to replace the BMW e60 tyre dimensions from 225/50R17 to 205/55R17. The 205/55R17 is not found on the recommended vehicle tyre dimension list.

The rolling circumference for the 225/50R17 is 1980.86mm whilst the 205/55R17 is 1982.37mm

In my case speedometer reading is not an issue.

Assuming that winter / snow tyres are “ideally” of smaller footprint width with higher side section height, there might be someone that might have been using this tyre size.

Does anybody have the experience / problem using the205/55R17? i.e. iDrive warning, “false” flat tyre indicator warning, brake and driving control systems failure or warning; etc

Thank you

turboawd

How is a narrower tire going to help for road conditions?
Your rim will be more prone to curbing since you'll have a narrower tire. Plus a narrow tire will look odd.

FormerE30Owner

You shouldn't have any problems with that size. All those systems
operate on comparing wheel velocities after being calibrated and since you are basically running exactly the same rolling circumference, the systems don't 'know' what width your tire are.

In fact your speedometer will indicate a more correct speed, since the stoch size yields about a 4% optimistic reading!

You are correct in assuming that the narrower tire will perform better in your road conditions - you are talking snow and slush conditions, correct?

Salut, Bob P.

JayArras

Yannick, you have received some good advice on the other forum. The Tire Rack recommendation is a good one. They are very nice people and very knowledgeable.

It sounds like you need a high sidewall to help protect against potholes. A narrow tire won't necessarily help you with that. But the TR people will steer you right.

audiophool

You're OK for the diameter, watch out for the load rating though. Keeping the same sidewall height for the 205 won't help if it's potholes you're worried about. You'd need a smaller rim size (assuming you could fit a 16" wheel) to get a taller sidewall. If narrower footprint for winter is your goal, the 205 will be a help.

RTSR1

I went from 225/50X17 to a 225/55X17 for better ride comfort and to correct the speedo that was off 4mph according to my GPS. The difference in ratio put it spot on! It also filled up the wheel well better. The ride is much improved!