Spare Tire Recommendations

Hello Tundra owners,

Need some recommendations/help regarding what SPARE tire and wheel size to purchase. My truck should be delivered next week and I'm getting stoked.

The wheels are TRD 20 inch alloy with Yokohama 285/65r20 tires (34.6 inch diameter). I did get the 3" lift. The spare wheel size I'm told is 18x7.

I've read through the forums and it seems like I can fit a 35 inch tire under the bed with a little coaxing, though the dealer tells me that is unlikely.

In a perfect world I'd just get the exact same tire and wheel combo and use it as a spare. I assume the wheel diameter wouldn't matter too much, just the total diameter of the tire, so I'm thinking a 20 inch wheel would fit with a fifth Yokohama tire of the same size. Is there anything stopping me from doing this?

I could keep the stock spare wheel (18x7), but don't know if I could find a tire with a similar diameter to fit a 7 inch wheel. I've got 4WD, so want to get the overall diameter as close as possible not to screw up the rear differential should worse come to worst.

A third option would be to purchase a 18x7.5 steel wheel on the cheap, and then buy another Yoko, but in 295/70r18 (34.3 inch diameter).

I feel like I'm going in circles. What say you Tundra masters?

Thank you in advance.

 

People are gonna hate it, but here's what you do. Nothing.

I assume you aren't doing anything too crazy off road with 20" wheels. So, we are mostly just worried about getting a flat on road? No problem, you get a flat, stick you tiny spare on a front corner and drive on. It really won't matter with the ADD and in 2wd.

Can you fit a 35 under the back? maybe. Might even have to let the air out to get it to fit. Issues you are gonna have are since you let the air out of the tire, dirt and crap is gonna sit on the tire and get between the tire and the bead for when you go to fill it back up, so it may not seal. Also it won't keep you nice 20" wheel looking very nice under there.

Or just toss a used 18 tire on the wheel you already have and try to cram it up there. Probably practice with a wheel/tire you already have though.

Or just do nothing...

 

@_none_

I like your reasoning. Often times we forget that doing nothing is always an option.

And you’re right (probably obvious) that I’m not doing any serious off-roading. I’d like to when I have more time, but most days it’s the eternal struggle of me against the clock. At most I’ll hit a few dirt roads, drive on the beach, and maybe see snow during the winter.

Still, I do want to get the diameter close. I’m leaning towards just getting a cheap steel 20 inch wheel and slapping a matched 285/65r20 tire on there, used if I can find one.

 

I went the other route and got 5 new wheels and tires. They are 295/60/R20 tires and I think they came in at ~34" I was able to stuff the spare in its spot and it fit fine.

My concern was more about doing damage to the differentials by spinning different sized tires. And there were some early reports about the front differential just packing it in so I figured it would be better overall, I could be wrong.

 

It's a differential. It doesn't care about different sized tires. Every time you turn, the left and right turn at different speeds. You can drive in circles all day and the truck won't care one bit.

 

And when in 2wd, the right front is totally disconnected from the diff anyways with the ADD. Even the left is essentially only spinning the spider gears inside.

You figure cars have donut spares which are smaller diameter, same principle.

I'd be more worried about the ABS spazzing out and probably just throwing a code.

 

I have a 35x12.50 mounted under my truck with all the stock parts. No modifications required. It's tighter than stock, but it fits. You basically have to keep one hand on the wheel while you crank it up so that it nests up there at the right angle.

 

The gear oil and rear differential will care. When I was a tech, we had an S10 blazer come in that had a flat rear tire, on the donut went, and they drove home 100 miles. The smell of that gear oil still haunts me!