cobra611

Good evening. I have an extra set of tires that came off my ‘09 TL SH-AWD. They are 245/45/ZR18 Continental Extreme Contact DWS. I was going to give them to a family member who needs tires. She has an ‘10 RDX. Could someone please tell me what the stock wheel size is for the ‘10 RDX, and if the tires I have, would fit? Thanks in advance!

IgottaTLyousomething

iTrader: (1)

Factory is 235/55/18. The new to her tires would fit no problem but it may be a slightly stiffer ride with the lower profile and the speedo will be slightly off too. Nothing to worry about in my opinion though.

Mr Hammond

18x7.5. The tires will fit, but the diameter difference is fairly significant. Stock 235/55/18s are 28.2 inches tall on average. 245/45/18s are 26.7 inches tall on average. Pros are better handling, braking, and acceleration. Cons are harsher ride and decreased fuel economy. They’ll fit though if she’s in a bind.

toddrhodes

iTrader: (1)

1.5" difference in tire height will throw the speedo off substantially as well. You'll be going slower than indicated and it gets exponentially worse with speed. So you may be off 2-3 MPH at 40 MPH but you could easily be off 5 at 70 MPH with that big of a difference. There are online calculators for that, like here:

https://tiresize.com/calculator/

Ran the calcs and it's not quite as bad as I thought, but still, not great: