How much of a variation in tire size is acceptable when replacing tires?

I can’t find any used tires in the Dallas area for my 2001 2WD Jeep Cherokee Sport. I bought it with 215-75-15, but I guess it came from the manufacturer with 225-75-15 because that’s what I get when I search for tires online based on the model.

Could anything bad happen from driving around on the wrong width tires the whole time? I can’t imagine 5mm would make much of a difference.

To add to the confusion, Sears gives different tire sizes for different 2001 Cherokee trim levels: 215-75-15 for the SE, 225-75-15 for the Sport, and 225-70-16 for the Classic and Limited. I thought the only difference between the trim levels were interior stuff like power windows. Could Jeep be equipping the different trim levels with different tires based on expected use i.e. someone with the SE probably won’t be doing much offroading so doesn’t need the extra tire width?

I guess the main impetus for my question is me trying to be cheap. The 215’s are cheaper than the 225’s and I’d like to stick with those(I have driven over 70K miles with them) unless it is not recommended.

That’s not a big difference. According to this handy calculator:
http://www.miata.net/garage/tirecalc.html
if the 225 tires are stock, your speedometer will read 2.1% mph fast with the 215s. When the Jeep’s speedometer reads 60 mph, you’re really going 58.2 mph. If the 215 tires are what the car came with, the speedometer will read 60 but your speed would be 61.3 with the 225s.

They can fit 30/9.5 tires but on some Cherokees they occasionally rub the control arm at full turn. I can’t look up the metric equivalent at the moment but I’m pretty sure that’s larger than what you’re talking about so you should be fine.

I’ve routinely gone up a width (and usually in quality - performance-wise) when I replace OEM tires. Most vehicles can accommodate that extra quarter-inch on each side and often have optional tire sizes one or two widths up from basic stock. (The first number, by the way, is the width of the tire at its widest point in millimeters - so you’re looking at the difference between 215 and 225 millimeters, or about 1/3 of an inch.)

Maintaining the overall rolling diameter is much more important, and your tire shop has that information on hand. (So does TireRack.com, if you want to search for yourself.) There is sometimes a slight difference in diameter based on section width times tire proportion - that’s the second number. It’s approximate within about 10%, but a 215/75 means the section width is 215mm and the overall rim-tread height is 75% of that. In theory, going up to 225 would mean a slight increase in tread height, but in practice the differences across common sizes are negligible.

It’s unlikely to matter on your Jeep, but narrower tires promote better fuel economy - I suspect that other factors in the road horsepower and drag on a Jeep would make the difference between otherwise identical 215 and 225s disappear into the statistical noise.

In the end, the only real difference is price. If saving $20 or so by holding out for the 215s is worth it, do so; if not, get what the shop has and is still a good fit for your vehicle.

Oh I misread, he wants the smaller tire. Yeah, it won’t hurt anything.

Here you go. I was looking to replace the run-flat tires on my MINI and had a devil of a time finding the exact size replacement tire. I finally found this website. Just plug in your numbers and it will give you comparable sizes.

http://www.tiresizecalculator.info/m/calculate.php

Different tire sizes on different trim levels is pretty common on SUVs. Usually the bigger tires also come with snazzier rims, which may be a different size or offset, so you can occasionally get into trouble there if you’re mounting a different sized tire on a rim that isn’t designed for it. But if you haven’t had trouble with that size thus far it should be fine.