Tires: changing wheel size from 15 to 16, goodyear wrangler, wheels and tires

Question
Thanks Andrew for the reply.  
So if I did go ahead and purchase the new 16" wheels and tires, could I still use the 15" full size spare in an emergency, or would that damage the vehicle somehow when driving with one different size wheel and tire?

Jerry
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Followup To

Question -
I have a 1998 Isuzu Rodeo S 4x4 that I purchased new from the dealer. The wheels and tires that came with it are 15" painted steel wheels and Goodyear Wrangler P235/75R15 tires. The tires have 81,000 miles on them and need to be replaced.  I went to get a quote on new tires and wheels (paint is chipping off the wheels, so I wanted to price wheels also) they told me that I could get either 15" or 16" wheels and tires and that there would be no issues with going up in size as far as tire rub or any other negatives.  They also told me that they show that the original wheels for my Rodeo were 16" and that the dealer may have switched them out or something, but in any case there would be no problem going to the 16" wheels and tires especially since they showed the vehicle should have come with the 16" wheels.  I was also told that it would not be a problem using my current full size 15" original spare tire as an emergency tire with the new 16" wheels and tires.  Would using the different wheel/tire spare cause damage to the vehicle?  Would it be okay to switch form the 15" wheels and tires to the 16"?  Are there any other concerns I need to know about?  The wheels he recommended are American Racing 16x8 6-5.5 type 136 with Toyo P245/70R-16 106s Open Country H/T tires  or the American Racing 15x8 6-5.5 type 136 with Toyo P235/75TR-15 Z-800 ultra whitewall tires. I'm not sure, but aren't the z-800 passenger tires and would that be a problem/ concern because I do infrequent trailering of a tent trailer and I thought that LT tires were recommended.  

Thank you,

Jerry

Answer -
Hello Jerry!

Sounds like someone has been doing their homework! Your correct in the 16" wheels is what factory on your truck, that being said I like your choice in the American Racing 16x8 6-5.5 type 136 with Toyo P245/70R-16 106s Open Country H/T tires combination. I'm not much of a fan of Toyo tires, but no matter what brand you pick you'll want to stay with a light truck tire application because a passenger car tire on any SUV is just a huge mistake and potentially a danger in waiting due to the difference in sidewall stiffness plus they will wear quicker. But, in your size(245/70/16) I don't know of any passenger car tire available in that size so no problem there. Anything else let me know!

Andrew ;)

Answer
Hey again Jerry!

Sorry, that I left that part of the answer out! :(

You will be okay in using the 235/75/15 as a spare only to use it for a short period of time until you can get one of the 16" tires repaired or replaced. There is not a huge difference in diameter between your two sizes so no damage should occur. Let me know if you need anything else!!!

Andrew ;)