When should tires be replaced on a 4x4?

[SteveInLA]

My Quadvan Sportsmobile has 21,000 miles on the original Nitto Terra Grappler 275/70R18 tires. If I compare the tread depth to the unused spare, I would say I have worn down a little more than half the tread. If this were a street-only vehicle I would say I could put on many more miles before I replaced them, but I want to maintain off-road performance as well, especially for the upcoming trip to Death Valley. At what depth do I need to be concerned about losing off-road grip? Truthfully, I am looking for an excuse to put on a set of the Nitto Trail Grapplers in a 295/70R18 size, but would it be foolish to pull off what might be perfectly serviceable tires? Would they have any resale value on Craigslist?

Steve in L.A.

[sdwindansea]

Steve, I can't answer your question about when to replace, although my guess is they should be fine for another 10k miles based on your description.

However, if you do replace them, I would recommend not going with the Nittos if longevity is a concern. I had the same tire and only got about 35k miles out of them and that may have been pushing it a bit.

[TwoVans]

Sounds to me like you CLEARLY need a set of tires for local driving and a set of off-road trips for excursions...

[Carl]

I originally ran Nitto tires which did seem to wear quickly, and I would agree that you may have another 10k or so left.
I made the switch to the BFG AT's in slightly larger size.
In my opinion the BFG's are better in every regard.

[rob_gendreau]

You didn't say how old they are. You can check the manufacturer's date on the sidewall (that may not be very close to when you bought them BTW). Age can affect their performance as well; I had to replace my last set of BFG T/A KOs due to age, not wear. Sunlight can affect that as well (my spare fared much much better, especially considering I won't use it for much).

Pictures would be helpful.

Rob

[jage]

Whatever you do, go bigger.

No but seriously, my Nitto ATs on my F250 wore like garbage- to the point where I had the option of getting some cash back for mileage warranty. I love those tires but the tread life made it totally not worth it. I sold it with them on.

As far as resale, it depends on where you are. You can't get $100 for a new spare once it touches the ground in Indiana, but in Colorado they're "nearly new" price half worn- at least that's what people are asking. Do a little craigslist search and price accordingly, if they don't get any interest, knock them down. Budget offroaders looking to up size will be your best customer. Regardless I think it's worth it to resell them if they have life- someone will want them.

I've still got Nitto ATs on the van, waiting to see the wear/life. I went with Toyo ATs on my little pickup, but it's in the featherweight class so doesn't really compare to the van.