khant

Hi folks, I'm in need of a spare tire as mine 18 RDX (FWD) didn't came with one. I called a local tire shop and they recommended me the B & R auto wrecking shop which has a 2010 and 2012 RDX on their lot to be salvaged for parts.For both of them the rim size is 18x7.5J and the tire size is 235/55R18. My question is these rims and tires compatible with my 18 RDX? And will they fit in the cargo area for the spare wheel? On my vehicle near the driver side I found the note specifying the rim size which matches the 18x7.5J but the tire size is 235/60R18. Please help me interpret these numbers/letters correctly so I can buy the right size. Thanks!

Kelsen

First, the rim size is compatible. In the US market, the factory rim size of the Acura RDX did not change until the 2019 model. The difference in the tire size is (60 on yours vs 55 on the two older models) is the aspect ratio of the tire - the height of the tire expressed as a percentage of the width. That means that if the tire was 10 inches wide (across the tread) and 6 inches from the (mounted on a rim) inner edge of the tire out to the beginning of the tread, the aspect ratio is 60 -- the height of the tire is 60% of the width of the tire.

The rims from either of the two salvage vehicles you have found will bolt onto your car perfectly. I don't actually know what kind (if any) of damage would be done running one tire with a lower profile than the other three tires. It may be only that it would feel funny. I would probably buy the salvage rim and put a correctly sized tire in it, in case you need to mount it.

Finally, because the 55 aspect ratio (height) is less than the 60 that your car was built for, the salvage rim and tire should fit the spare tire wheel well with no trouble at all.


RFT!!!
Dave Kelsen
--
It's hard to explain puns to kleptomaniacs, because they take things literally.

Fastfoodie

The 235/55-18 tires will be fine for temporary use. It is best to run four tires of the same size as different sizes can wear your differential and cause issues with the stability control system wearing the brakes even on FWD vehicles. I run four 235/55-18 as my winter tires and have had no issues.