Tires should be the same diameter when you have an AWD vehicle, but exact tread pattern is less critical. However, it will have a small effect on handling and steering, so I would prefer to have matching front tires if possible. Just drive sensibly until you get the road tire repaired.

 

If the car comes with a donut spare isn't that telling you it won't have any issues with differing size tires?

 

Yes logically speaking it absolutely does and I thought of it but my OCD never allows me to be fully at ease, hence the need to double check against actual experience, mine or others.
If you look at specs of the same size tires, but different models, even of the same manufacturer, they will have slightly different number of revolutions per mile, cause actual diameter is slightly different for different types of thread. That is enough for me to start wondering about consequences...

 

You haven't actually said which 4.5 year & model RAV4 you have.

 

Sorry forgot- 2019 Adventure.
I actually just made my decision, will go in a different direction- Yokohama Geolandar X-CV. Discovered them by chance on the Yokohama website while I was researching the Geolandar A/T and they piqued my interest.
Supposed to be a great compromise between wet, dry, snow performance and ride quality.
Given how little time I spend off road they make more sense to me.
Will see how I like them once I swap them in a week or two.

But, back to my original point, I still plan on keeping one old Toyo Open Country as full size spare in the trunk. I hope that won't be a bad idea.

 

One of the benefits of having a full size spare, it became part of your tire rotation . Prolonged your tire life by a couple of years.

 

Your Subaru info is factual, but the Subaru AWD system is completely different from the RAV4, which makes their guidance relatively useless. For example, my RAV4 Prime runs the rear wheels off a separate electric motor, which means no transfer case or center differential to have any wear.

I had the same issue when I needed to replace a tire on my BMW with xDrive, and the service guy at the BMW dealer had just transferred from a Subaru dealer. Everything was within BMW specs for wear, but he was quoting doom and gloom from Subaru guidance.

 

Your Subaru info is factual, but the Subaru AWD system is completely different from the RAV4, which makes their guidance relatively useless.

Right on point. Subaru uses a viscous coupler (not a center differential to my knowledge) to facilitate AWD, to allow slippage in the driveshaft while cornering. Toyota doesn't use any such device on ANY model. That's what frosts me when the service techs call the active variable electromagnetic coupler on the 4.3s a stupid dumb viscous coupler almost like they stole one off a Subaru.

 

Here's mine.