Thread: 19" Maxxis AT Tyres

Originally Posted by ShawnWang

Hi guys

How's your Maxxis AT980 doing? Want to hear your story and update. What tyre pressure are you using when off road?

I bought a set At980 255/55R19 a month ago and I had about 2000km on them. when doing offroad trips, I reduce the tyre pressure to 25 psi. Unfortunately, last weekend, I had a sidewall cut/damage (left rear tyre) on a fairly easy rocky track. Feeling disappointment. Did I low the tyre pressure too much? Some threads recommended >32psi. What do you think?

Thank you.

Shawn

I think 25 psi is an appropriate pressure. I reckon you were just unlucky. Speed and vehicle positioning is always a factor. The lower the pressure the slower the speed, and with the capability of the Disco you don’t need to go too fast at anything.

David

Originally Posted by Odysseyman

I think 25 psi is an appropriate pressure. I reckon you were just unlucky. Speed and vehicle positioning is always a factor. The lower the pressure the slower the speed, and with the capability of the Disco you don’t need to go too fast at anything.

David

I was in a convoy at speed of 30km to 45km. I think that corner bagged a bit more than other wheels with the same tyre pressure. There was a scratch on the sidewall as well besides the deep cut.

>I think 25 psi is an appropriate pressure.
I'm not so sure about this. Note that I know nothing about Maxxis AT tyres. But, with regards to rocky tracks (e.g. Vic high country) in the old 750x16 bar tread days 25 to 28psi worked well. Radials tended to up that to around 32-36psi. But in the D4, even at 38psi (255/55 R19 Goodyear Wranglers), I was horrified at how the sidewalls bulged. Personally, unless it was very very wet, I would run F&R pressures well into the 30's virtually anywhere in the high country.
I also run a set of Kuhmo MT51 265x60R18 LT on Compo rims. I just spent 14 days hunting up in the high country and the pressures remained at 34psi front and 38psi rear the whole time. The secret is to drive as slowly as possible and pick your line. In nearly 50 years of serious off road driving (all Landrovers) I can only recall one occasion when I damaged a sidewall (it may have been already damaged but gave way at a most inopportune time!) and that was a 750x16 8 ply Olympic Steeltrek? Forget. Whatever the army used to use on their Series IIIs. Only other time was my own silly fault in the Rangie when I was too lazy to drive a bit further up the track at the farm to turn around and ventured into some thick fallen timber and staked a perfectly good AT tyre.
Don't get me wrong. I've replaced tyres that were clearly sidewall damaged as part of preventative maintenance and I've had my share of nails etc embedded in treads causing slow leaks. But my recommendation is to keep tyre pressures on the high side in rocky terrain, drive slowly and pick your line to allow the tyres to do their work without being shock loaded.

This is the conundrum. Lowering the pressure is better for the track’s health by reducing ruts and corrugation creation, but runs the risk of damage on the 19”. All 19” are highly susceptible to sidewall damage on rocks as there just isn’t enough room to flex before the rim hits at lowered pressures. Unless you’re on soft sand I’d recommend you don’t lower substantially. If you knock 6-10psi out of road pressures you’ll likely survive. I tend to run around 36f and 42r when towing. If you took 10psi off that you’d probably be ok. Bear in mind that I’m talking cold pressures at the set point. They will increase at least 4psi preferably but up to 10 depending. I’d recommend tasking the pressure off the hot pressure not the cold too.

I have no perfect answers but having totalled two sidewalls now I’m getting bored of low pressures and 19”. To be fair though, one was an unidentified rock under water and the other was a rock in the track I didn’t see. At least one was avoidable.

25psi is too low for 19” and in my experience not required except for soft sand.

Scott

Originally Posted by LRD414

25psi is too low for 19” and in my experience not required except for soft sand.

Scott

Agree. Let’s not forget that we really need to differentiate between front and rear. There’s a reasonable gap front to rear at max pressures. You cannot use a blanket pressure across both ends.

Thank you for your feedback, guys. Next trip, I will try 32psi front and 36 psi rear. Hope not to have problems on steep tracks.

I run 40psi in mine. When towing, 48 rear(2.5t camper).
I was up the Barringtons a couple of weeks ago and did some trail work (with sharp rocks), and it handled it very well.
If I ever do sand, I’ll try 25-30 and see how it goes.
These are great tyres IMO.