Rep Power: 0

I want to install tires from Costco they won't allow anything taller than stock 195/60/15.
I've had 205/65/15 since last time and I wanted 195/70/15 which is taller and also cheaper and it does better mpg on highway at lower RPM.
I need long lasting 80,000miles good lower cost tire that will last, I do full time Ubereats on my Honda Civic 2005 lx, only car I have had since 0miles.
I was also worried if taller tires might damage the transmission? Hi and Thanks a bunch you people

 
Rep Power: 125

Use a tire size calculator. Anything within 3% is fine. Costco will install anything within 3% of the stock tire size, which is 195/60/15.
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https://tiresize.com/tyre-size-calculator/

Run your tire size through that, and it'll give you a variety of other sizes you can use.

If you stay within that percentage, your transmission will be fine.

Also, I saw your post on a different thread. Costco will swap tires other than 195/60/15, but they need to be within the spec ratio, which the tires you had on before were not. The 205/65/15 are off by more than 5% and the 195/70/15 are off by more than 6%. For example, Costco will swap a 205/55/15 or a 185/65/15. I brought in a set of 17's and they were more than happy to swap 195/45/17 onto the same car. If anything, you were doing more damage to the transmission on your older tires.

 
Rep Power: 223

Won't really do any damage to the transmission but it would make your speedometer and odometer incorrect if using a size not within ~3% of original.