I've been noticing that my speedo and actual speed are approx. 5-6% off (with the speedo figure being higher) and realized this was due to the tire's lower tire aspect ratio - 35 instead of 45 (why that's the case is a separate story). I understand other than the speedo being overestimated, it will also impact the as indicated mileage figure of my vehicle. Since the tires are somewhat new and I haven't sensed any ride issues, I can live with this until the tires get replaced. However, would there be any long term technical issues to the vehicle components, suspension etc., that I should be worried about?

 

On older cars you used to be able to correct the speed difference by changing a gear in the speedometer. I am wondering now if there is an electronic setting somewhere that maybe the dealer could change to correct the speed difference?

 

Almost all new cars these days leave the factory with the speedo over-reading (optimistic) by some 4 or 5 mph, and that's even a legal requirement in many countries.
The common rule/law is that a speedo can NEVER under-read but can over-read by up to 10%.
It's all for saaaaaafety doncha know, we can't allow anyone to inadvertently exceed the speed limit even by one MPH, doncha know that doing so is the biggest cause of crashes by far?