New Tires


#1

I recently purchased a set of 4 tires for a 2004 Toyota Highlander, 2WD. The tire shop installed size 235/70/R16; However, this size is not compatible with the spare, which is 225/70/R16. Would this be a problem if I had to use the spare in case of a flat, etc. ( I’m thinkin’ donut which is much smaller than normal tires, anyway).


#2

The difference in overall diameter is very small. Since this is a 2WD, you don’t have to worry about unmatched tires causing problems with the center viscous coupling.

Just don’t include the spare in your tire rotations.


#3

You can get a used tire a lot cheaper than a new one for the spare, and you don’t even have to balance it.


#4

Thanks for your response. I have a spare which was never used. I was just concerned about any safety issues if I had to use it with the larger tires.


#5

Thank you for your timely response.


#6

The differences are:

Specification Sidewall Radius Diameter Circumference Revolutions Speedometer Odometer Difference
225/70-16 6.2" 14.2" 28.4" 89.2" 710/mi 60MPH 10000mi N/A
235/70-16 6.5" 14.5" 29.0" 91.0" 697/mi 59MPH 9810mi 1.9%

A 2 % difference may not seem like much, but it amounts to a significant difference in driving over time with diff. tires on the same axle. It really can’t be treated like a full size spare. I would, as suggested replace the spare with a 235 or demand that the tire shop replace all fours with 225’s.
You have abs, trac control and stability control, all affected by the larger tires. May not be significant in performance, but as an ex cop who did plenty accident reports, it “may not” be something and insurance investigator would overlook. Son in law was one…it’s worth considering for liability purposes.
Sorry to be paranoid. I wouldn’t and don’t take the chances with tire sizes and electronic traction aids.


#7

I believe that the difference between the two tires is 235 mm wide vs. 225 mm wide. The diameter is the same; a 16-inch diameter rim with a 70% aspect ratio in both cases. I’m sure that for short distances the small difference in tire width would be OK. The odds are tha heplo5615 won’t need the spare anyway.

Added: I see my mistake in calculating the aspect ratio, comparing the overall diameter to the width.


#8

Thank you for your response. I went back to the tire dealer and purchased size 235 at half-price, with balancing included. Am very satisfied now.
Thanks.