Wider Tires

falcon1970

With the Boondock Lite option on a TAB 400,the pitched axle comes with wider (235mm vs 205mm) off-road tires.  Are the fender flares (the plastic splash guards outside the tire) also wider?

jkjenn

No, the Boondock offers a slightly taller and more aggressive tread, but not necessarily wider.

Apart from the height and look, I am not sure there are really benefits to off road trailer tires. Your TV tires are what do the work. As far as stability, I am not sure you could achieve much more with wider tires on a 400 or a 320, given the heights.
For me, the extra height and durability are the keys.

falcon1970

jkjenn said:

No, the Boondock offers a slightly taller and more aggressive tread, but not necessarily wider.

Apart from the height and look, I am not sure there are really benefits to off road trailer tires. Your TV tires are what do the work. As far as stability, I am not sure you could achieve much more with wider tires on a 400 or a 320, given the heights.
For me, the extra height and durability are the keys.

Actually, the Boondock option adds 235x75R15 tires but the non-boondocks tires are 205x75R15. The Boondock tires are 30mm wider but the aspect ratio is the same.  So the Boondock tires are slightly taller as you said.  My plan is to order the Boondocks axle but not the off-road tires.  Like you, I don't see the value of "knobby" tire on a non-driven axle.  In fact, an aggressive tread may actually be a detriment on smooth pavement and of no utility off-road.  In the future I plan to put light truck tires on the trailer but I guess I will stick with the 235 size since the boondock option doesn't extend the fender flares anyway.

WilliamA

jkjenn said:

No, the Boondock offers a slightly taller and more aggressive tread, but not necessarily wider.

Apart from the height and look, I am not sure there are really benefits to off road trailer tires. Your TV tires are what do the work. As far as stability, I am not sure you could achieve much more with wider tires on a 400 or a 320, given the heights.
For me, the extra height and durability are the keys.

That's not entirely accurate.  The tread pattern is to help keep the trailer from sliding sideways in slippery (muddy, wet, slick) terrain.  In addition, the offroad tires have more sidewall protection to guard against punctures from rocks and sticks.  Most folks don't have a switch for the electric brakes so when hitting the brakes in off-camber spots, there's less chance the trailer brakes will lock up and cause the trailer to swing violently downhill.  The offroad tires are stronger and better in just about every way.  Plus, stiffer sidewalls equal less sway at a given pressure on the road.  A wider tire has more volume for a given diameter hence, higher load capacity.  The trade-off (always is!) is that a wider tire will run hotter (more friction surface) than a tall, thin tire of the same contact area. The wider tire will have higher rolling resistance.  Taller tires have a larger contact patch longitudinally with less friction from flex, but also need higher pressures to prevent overheating from sidewall flex.  It's the same reason tall bicycle tires (29'ers) have less rolling resistance than 26'ers.
WilliamA 

MuttonChops

WilliamA said:

  . . . offroad tires have more sidewall protection to guard against punctures from rocks and sticks. 

I factory ordered a 320S with the pitched axle and considered asking for T@B 400 205/75/15 ST tires to get maybe a small percentage of higher MPG but in the end went with Outback All-Terrain 235/75/15.  NuCamp had already said No to a MaxAir Fan and my dealer didn't think asking for 205 tires would get very far.  And who knows maybe that extra 3/4 inch of side wall will be important someday.

The trailer arrived with XL rated Truck/SUV tires  XL designated tires have additional material added to the shoulder of the tire for extra strength however it is not clear to me if XL tires are as 'good' as ST rated tires. 

One source defines 'ST' tires as ST tires utilize materials and construction needed to handle the higher loads trailers present. ST rubber compounds typically incorporate more chemicals to resist UV rays and aging, and may also use harder rubber than drive wheel and steering tires. ST tire sidewalls are designed to keep the tire from rolling off or under the rim during tight turns. Cords used in ST tires are larger than those in comparable Passenger (P) or Light Truck (LT) tires.

N7SHG_Ham

I believe an ST tire is the preferred choice on a trailer. It sounds like the Boondock tires are NOT ST tires and that is interesting that an OEM would do such a thing. I have never seen an ST tire with "off-road" tread, but I suppose they may exist?

Spectre9

I just bought a 2018 Outback 320S and it had ST off-road tires rated for 75mph max.  I can lookup brand next time I go to storage.

MuttonChops

Spectre9 said:

I just bought a 2018 Outback 320S and it had ST off-road tires rated for 75mph max.  I can lookup brand next time I go to storage.

Please do.  I've searched & searched for ST type in the 235/75/15 size with no luck.  Did find lots of 225/75/15 highway tread.

Include all detail if possible: Brand, Marketing Name on sidewall, full sidewall marking for tire size/type.

Sneakle

Here are the tires that came on our 2018 320s boondock. 

MuttonChops

Sneakle said:

Here are the tires that came on our 2018 320s boondock.

Yep, same as installed on my Feb-2018 build; pitched axle + Boondock tires.

While I have no worries about these tires ( they have very high speed & load rating compared to a 320 GVWR) but they are ' XL ' not ' ST ' construction style.  Which means they have stronger side walls for off-road rock impact protection but aren't true trailer rated tires.  {see earlier post in this thread on XL - ST}