Prius Prime and spare tire

Both of my AWD Venzas came with donuts. No choice.

 

My understanding was that Sienna AWD had a drive shaft and rear differential that prevented mounting spare tire underbody of the car like FWD model Sienna. This design has not changed in over a decade. If your AWD Venzas came with spares, that means Toyota can design AWD with a compartment for spare. I have no idea why the can't do it for Sienna.

 

You mean the rear differential that turned into a great lump of rust? That thing was was wrong on so many fronts.

It ticks me off to hear a car company say they can't do something because... Our daughter's 4WD Pilot has a rear differential and a full size spare. It's a royally inconvenient location, underslung, but it's doable.

 

Yap, that's the one. In retrospect, we probably did not need AWD minivan. Our previous 3 minivans (2 Quest and 1 Grand Caravan) were all FWD. We bought it after moving more North, and the Sienna was the only minivan model that came and still does come in AWD. If we bought FWD Sienna, it would still be running great today.

But I bet Pilot or any other AWD SUV has the ability to stow away the third-row seats like most minivans. Also, SUVs probably have much better ground clearance than minivans. My old Pathfinder had a Swing Arm Latch full-size spare carrier on the tailgate, but I have not seen a carrier like that on a minivan.

 

Yeah 4WD is a big complication for servicing.

 

The minivan was likely designed to maximize interior space. Then Toyota probably stuck with run flats out of habit after the goo pump became available.

 

So I looked up the 2005 prius spare size and it's a 125/70/16. That means the overall diameter is about two inches smaller than the stock wheels. Could you or anyone more knowledgeable than me confirm that this is the case? If so it might be the most space saving size to carry.

 

Just off the top of my head: the temp spare outside diameter should be very close to second gen full size tire size, at most a 1/8" difference. So, it would be slightly undersized for 3rd or 4th gen.

 

Very possible. I'm going by this 125/70-R16 vs 195/65-R15 Tire Comparison - Tire Size Calculator | Tacoma World

 

Well my tire calc spreadsheet corroborates what YOU say:



It's very odd that the second gen temp would so much smaller, than a second gen stock tire. Maybe look up that temp spare size on TireRack, see what they say for the OD.

 

I think my calculator is messed up: when I put in third gen temp, it report it also as being significantly smaller than stock tire OD. And I know that's not true, because I've set my 3rd gen stock tire and the 3rd gen temp tire one atop the the other, and checked the difference by running a carpenter's square up to them. It was at most 1/8" smaller.

Based on that, I'd say a second gen temp spare would undersized even more, likely more like 3/8" less on the diameter.

Also a second gen temp spare would be getting on, rubber getting old.

 

I personally wouldn't run a T125/70-16 on a Prime, they're about ~22.9" OD vs the Primes 25" OD; this represents almost a ~10% difference which is very BIG when matching tires.

OE 195/65-15 = 836 Revs Per Mile
T135/80-16 = 850 Revs Per Mile
vs
T125/70-16 = 907 Revs Per Mile

Months ago I bought a new/used T135/80-16, this size is virtually perfect for a Prime because they're 24.8" OD, plus their load capability is more than 250 lbs greater when compared to the smaller 125/70-16.




Rob43

 

If you put on an undersized tire it will maybe throw a code, speed sensors will detect it?

 

Many of the spare tires I've seen in use are undersized. These are only meant for temporary use with a recommended max speed of maybe 50mph. In addition to saving weight, an undersized tire will also encourage people not to speed on it, and to replace it.

Could the cars in Canada have gotten a larger spare?

 

No, same sizes I think. I believe it's just my spreadsheet calculator messing up.

Third gen, North American Owner's Manual spec for temp spare:


Tire Rack info for one such tire:



LInk for above:

https://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=Y870B&partnum=38MD6YOTEMP


Second gen, North American Owner's Manual spec for temp spare:



Tire Rack info for one such tire:



Link for above:

https://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=CST+17&partnum=27MR6CST17&vehicleSearch=false&fromCompare1=yes

Addendum: second gen tire rack info updated.

 

the one in the manual and the one on tire rack are different aspect ratios. 70 in the manual, 80 on tire rack. The one in the manual has approximately 23 inch od.
2nd gen spare = 23od
3rd gen spare = 25od
4th gen spare= 24od

 

Doh, good catch. Lessee if I can fix that post. I agree 4th gen spare spec is looney tunes btw: stock 3rd and 4th gen tire is same OD, so why oh why did they undersize the spare. Follow the money I guess.

 

True and yet the reason I posted in this thread at all is because someone used the 2nd gen without issues on the prime. I need to save space. I drive long distances with a full trunk and park in areas where I can't have anything visible left in the car. The load rating on the 2nd gen spare is higher than needed as long as you keep it inflated, which I do. Seems like the best option if it's true that it worked without throwing lights.

 

I would get a third gen spare if practical. Or a second gen temp spare rim with 3rd gen spec temp spare tire.

Notable: according McGeorge Toyota Parts website, second and third gen temp spare rims are the same:



1992-2010 Toyota Spare Wheel 42611-20841 | McGeorge Toyota Parts



1992-2010 Toyota Spare Wheel 42611-20841 | McGeorge Toyota Parts

 

I'd like to use this type of setup to secure it Tying down spare? | PriusChat by @ppongi

I don't understand the description though. It mentions a sunshade in the trunk. Mine has the retractable cover which is removable.
Any ideas?