Wheel/Tire Size Question

[AGENT SMITH]

Hello everyone, this is my first actual question post on this forum. I've got a 2008 Trailblazer with stock 245/60/18s and have been researching what I would need to lift it and get bigger tires. I've noticed there is a lot of discussion about 17" wheels and required mods for fitting larger tires on them, but not much info on 18" wheels/tire options. For whatever reason, 18s don't seem to be as popular even though they came stock on the 08 TB. Why is this, and does this mean that I'm going to need to switch to 17" wheels to have more tire options? Any help or direction would be appreciated!

[Trail X]

Only a few model years got the 18" wheels, and they are generally the later model years, so they are not as popular on this site.

But anything you see referenced regarding 16" and 17" wheels can be applied to the 18" wheels, you'll just have to find the correlating tire for your 18" wheels. For instance, a 255/75/17 will be very similar to a 255/70/18. The only real difference will be the wheel diameter. Tire diameter and width are the same between those two.

[TBYODA]

Another member with stock 18" wheels. Make's me wonder if his diff is stamped with 8.6 or not.

[v7guy]

You'll hear some guys chime in that 18s won't leave much sidewall on the tire and that you won't get a lot of flexibility in the tire while climbing obstacles. In the real world is it gonna make a significant difference? I guess it'll come down to how tall of a tire you run. If you're running a 30" tire I could see it being a disagreeable combo, 35s you likely wouldn't notice much of any difference from a 17.
You gotta put it in perspective that the difference between a 17 and a 18 is going to be half an inch. In addition we've seen a lot of talk around here about going up to 17s from 16s to fit the bigger brakes... so I don't know if you really want to entertain 16s.

As a side note you can run wheels that really stick out and completely clear the brakes that way and even fit a 15, but I don't know if it's worth the trade off in scrub.

[AGENT SMITH]

Thanks for your thoughts. I was just becoming frustrated when not finding much in the 18" realm on the 'will it fit' charts and discussions. Though, you are right to say that I will just have to convert the 17" tire specs to 18s that have the same overall diameter. As far as the sidewall depth, I'm not too concerned with that since I don't plan on rock crawling. Just want to be able to handle some light to medium trails. My main concern with the 18s is that the selection wont be as great to choose from, possibly even in finding some lightly used tires to start with.

[mikekey]

The selection won't be that wonderful. I almost bought 18's myself when moving to 35's, but ended up just sticking with 17inch tires. Prices were also cheaper, for both rims and the tires. I will say, 18's have a better tire selection over 19's. I have them on my other vehicle (came factory) and the selection is limited. Vehicles seem to have went from 18's to 20's and most have stayed in the 20 range. I personally hate the giant rims. They're even putting them on trucks these days. They're selling you less tire for more money when you think about it.