If cash is available for new tires....get new tires.
According to Dr. Google, for the General Altimax RT45, the load carrying capacity is 1709lbs per tire for the 225/60R17 and 1874lbs for the 235/60R17.
That's a total of 660lbs of capacity difference. If this minivan just holds a couple kids and a few shopping bags every now and then it will probably be fine. If it gets loaded up to the gills often you might be exceeding the tire rating.
Look up the curb weight of this minivan and add the 665kg for allowed occupant/cargo capacity. That is the combined weight rating. Multiply the tire load capacity by 4 and see how it compares.
Curb weight 4365 lbs (according to Google) +665kg(1466 lbs)
=5831 lbs
1709lbs per tire for the 225/60R17 x 4
=6836 lbs
1874lbs for the 235/60R17 x 4
=7496 lbs
=660 lbs difference as you stated between the two General Altimax RT45 sizes
I'll forward her the thread. Money is tight so she'll probably lean towards using the extra tires in the smaller size of the tire shop will install them.
I will say Capri Racer not approving of the idea is a big red flag as I generally seek his posts out when it comes to tires
I appreciate all the responses. It does seem like it's doable to use the extra tires. She doesn't load up the van but there probably are 900-1000 lbs of passengers most of the time with a small amount of driving with nother 200-300 lbs? I'm just guessing.
The drawbacks seem to be that using the smaller extra set of tires could resulting in wear even faster than she experienced with the previous van and it may not corner or otherwise handle as well. Then again it's a minivan so she won't be driving aggressively (but the design of these Siennas over the years do seem to result in extra wear as a result of being under tired already with OEM size tires). Also I'm curious how much the van design changed from her 2008 to 2011 (one reply mentioned this was the first year that the tire size was increased to 235). If it was okay as OEM just three years, prior is it that bad to use these tires up on the current van?
A small issue would be the speedometer difference but it was mentioned it will read faster than the actual speed which seems better than actual speed being slower. I have dealt with this in my car and it doesn't seem to be a big deal.
The drawbacks don't seem to be as bad as when threads come up and people are told not to drive their 6-10 year + old tires or when there's a puncture close to the no fix area and some suggest to still plug/patch it and others say that's too much of a risk.
