[ajnanyc]

I recently switched from 19" to 17" and went for these 265/70-17 Nitto Terra Grappler G2's. No issues with ride, rubbing or noise. Main complaint is the noticeable decreased gas mileage and odometer discrepancies. Not to mention the elephant in the room, the huge full spare that sits in the cargo area that takes up the entire space! Does anyone know if the OEM 17" donut spare tire would work in a pinch, without doing damage to the drive train? I believe the current diameter to be 31.6", but I'm not sure on the size of the donut?

 

[noobytoogy]

I don't recall anyone asking that one before!

Tricky.

The slight difference in the overall diameter of the space-saver is dealt with by the car's electronics up to a maximum speed of 50mph/80kph. Thereafter it's not and that's why you can get transmission wind-up which may burn out clutches in the autobox unless the car is running on grass, ice, gravel, sand - any surface where the wheels can slip and self adjust.

Whether the system will accommodate a difference approaching two inches, I simply don't know.

The standard 235/65/17 29 inch OD will do 695 revolutions per mile versus your new size tyres of 31.6 inches doing 636. That's nigh on 10% difference.

https://tiresize.com/comparison/

I use and recommend tyre strings. Quite often you can fix a puncture without even taking the wheel off!

I've even used four or five strings to fill quite a big hole before now. Needless to say that tyre was a write-off but I did several hundred miles on it at sensible speeds until my new set arrived.

I like to use a little rubber glue with the string. Some kits have it, some don't.

I haven't used these but they're worth looking at:

 

[ajnanyc]

Very good points, thanks. I've used rubber string repairs on motorcycle/car tires before with success. They're actually a life saver on a motorcycle when you're miles away from civilization. Unfortunately not so handy on sidewall punctures, and given my last two incidents were both sidewall related, I feel that I definitely need a spare tire backup.