Tire Selection Help Please

[01tundra]

I've decided to replace the tires on our Hummingbird after watching the sidewalls bulging and the tires cycling up and down pretty much contiuously on our way home from camping this weekend.

The factory tires are P235/75R15 all-terrain (Baja Option) aired to 44 psi on aluminum rims.

The rims are rated for a maximum pressure of 110 psi. They are 15"x6".

The GVWR for the TT is 3,750 lbs an has a single torsion axle.

The CAT scales says it was at 3,700 lbs during our last trip, so lets assume it will be maxed out at 3,750 lbs. The tongue weight was weighed at 500 lbs.

I am interested in replacing all three (spare) tires with 225/75R15 Maxxis M8008 ST tires in an 8-ply (D-rated). I plan to run them at 65 psi. The tires will be approximately 0.6" smaller in diameter, resulting in 0.3" of lost ground clearance on paper, but since the tire sidewalls won't be flexing so much I won't actually be losing any ground clearance.

I know it is common for people to automatically say "go E-rated, 10-ply", but I think in my particular case that would actually be too much tire. I don't want a tire so stiff and over rated that it transfers excessive road bump energy to the TT.

At 3,750 GW - 500 TW the axle is carrying 3,250 lbs, so roughly 1,625 lbs per wheel. The 8-ply M8008's are rated for 2,540 lbs @ 65 psi, so the tires would have around 36% safety factor.

Am I thinking right choosing D-rated instead of E-rated? Or are D-rated still going to be too heavy duty for our TT? I know I definitely want an ST tire over these no-name P-rated all terrain tires that bounce continuously down the road....

Any thoughts or opinions?

Thanks.

[TCNashville]

Just curious why they would put a passenger car tire on the trailer in the first place. I guess ST tires don't come in an off road model? You might not want to go over a "D" rated tire. The sidewall stiffness between a "D" and an "E" is huge. If you put an "E" on there, It might just beat the crap out of everything inside every bump you hit. I switched to E rated tires but my camper weighs 9500lbs loaded. Is the 44lbs the max pressure listed on the sidewall on your current tires?

[01tundra]

No idea why they put them on, other than it's the Baja edition and they advertise it as having "all-terrain" tires.

Yes, tire sidewall and Jayco sticker both say 44 psi.

My thoughts exactly on E-rated, I think in my particular case it could be overkill. C-rated work fine on paper, but if it won't cause any issues I'd feel better with D-rated.

[eldermike]

Good choice and proper consideration of effects of your choice.

[01tundra]

I went ahead and pulled the trigger on three 8-ply M8008's, a few minutes ago, they should be here in a couple days.

Thanks for the input.

[oldmanAZ]

Originally Posted by 01tundra

I went ahead and pulled the trigger on three 8-ply M8008's, a few minutes ago, they should be here in a couple days.
Thanks for the input.

Thinking about that myself. Where did you buy them?

[01tundra]

Originally Posted by oldmanAZ

Thinking about that myself. Where did you buy them?

I was planning on ordering them from Amazon Prime for $112.37 each and having Discount Tire mount and balance them, but Discount sold them to me for $110 ea and the mounting and balancing is $4 less per tire if they supply the tires, so even with sales tax I came out better buying them from Discount. I even got them to throw in metal valve stems after the fact because I forgot about them until after I paid, I offered to pay but they said they'll cover them.

Tire will be here sometime this week, so I'm just going to pull all three wheels and drop them off instead of dragging the TT to them.

[bdreinv]

Originally Posted by 01tundra

I've decided to replace the tires on our Hummingbird after watching the sidewalls bulging and the tires cycling up and down pretty much contiuously on our way home from camping this weekend.

The factory tires are P235/75R15 all-terrain (Baja Option) aired to 44 psi on aluminum rims.

The rims are rated for a maximum pressure of 110 psi. They are 15"x6".

The GVWR for the TT is 3,750 lbs an has a single torsion axle.

The CAT scales says it was at 3,700 lbs during our last trip, so lets assume it will be maxed out at 3,750 lbs. The tongue weight was weighed at 500 lbs.

I am interested in replacing all three (spare) tires with 225/75R15 Maxxis M8008 ST tires in an 8-ply (D-rated). I plan to run them at 65 psi. The tires will be approximately 0.6" smaller in diameter, resulting in 0.3" of lost ground clearance on paper, but since the tire sidewalls won't be flexing so much I won't actually be losing any ground clearance.

I know it is common for people to automatically say "go E-rated, 10-ply", but I think in my particular case that would actually be too much tire. I don't want a tire so stiff and over rated that it transfers excessive road bump energy to the TT.

At 3,750 GW - 500 TW the axle is carrying 3,250 lbs, so roughly 1,625 lbs per wheel. The 8-ply M8008's are rated for 2,540 lbs @ 65 psi, so the tires would have around 36% safety factor.

Am I thinking right choosing D-rated instead of E-rated? Or are D-rated still going to be too heavy duty for our TT? I know I definitely want an ST tire over these no-name P-rated all terrain tires that bounce continuously down the road....

Any thoughts or opinions?

Thanks.

We live in Phoenix lots of folks here have gone to truck tires e rated.At least they have a tread wear number its 3 digits.The higher the number say 600+ the better the tire.On our car the tread wear number is 680 and the mileage warranty is 65000.Obviously no way to track mileage on a camper.It does give you a better feel on the tire quality.Hope that helps!

[norty1]

I keep very accurate records on towing. We keep a manual log and write the mileage down when we leave towing and when we arrive.

I can tell you exactly how many miles are on this trailer and on every tire.

[ttavasc]

Originally Posted by 01tundra

No idea why they put them on, other than it's the Baja edition and they advertise it as having "all-terrain" tires.

Yes, tire sidewall and Jayco sticker both say 44 psi.

My thoughts exactly on E-rated, I think in my particular case it could be overkill. C-rated work fine on paper, but if it won't cause any issues I'd feel better with D-rated.

This is interesting - and perhaps another "money-saving" feature. Our 2015 SLX Baja came with the same size but in an LT LR-C specification - 50PSI max pressure which is where I keep them. The GVWR on our unit is also 3750 and my scaled weight on the axle with WD engaged is 3260. I've not noticed any excessive bounce or bulging. I haven't been to the dealers in quite a while so I don't know if the 2017 SLX Baja's still use the LT tire or not.

[TCNashville]

Originally Posted by bdreinv

Obviously no way to track mileage on a camper.

On my '12 F-250 you can enter up 5 trailers [I think] in the on board computer and it keeps track of the miles on whichever you select. Once you plug in, it gives many options. The last time I checked, my Jayco had 3320 miles as we usually camp within 100 miles of home.

[Crabman]

Originally Posted by 01tundra

I went ahead and pulled the trigger on three 8-ply M8008's, a few minutes ago, they should be here in a couple days.

Thanks for the input.

Good choice. I don`t think it can hurt to go up a load range if the rims can take the additional psi and yours can.

[Bookemdanno]

Originally Posted by TCNashville

On my '12 F-250 you can enter up 5 trailers [I think] in the on board computer and it keeps track of the miles on whichever you select. Once you plug in, it gives many options. The last time I checked, my Jayco had 3320 miles as we usually camp within 100 miles of home.

Same with my Ram.

[bdreinv]

Good idea, funny how we forget the simplest things!

[01tundra]

Just finished bolting them on, got an M8008 for the spare as well.

As I suspected, didn't really lose any ground clearance with these tires since they hold the weight so much better.

Had metal valve stems installed on all three wheels in case I ever decide to install TPMS.

I appreciate everyone's help with this!

[TCNashville]

Very nice! Did you have them balanced?

[01tundra]

Originally Posted by TCNashville

Very nice! Did you have them balanced?

Yes, all three.

I did confirm that the weight rating for the wheels was 2,830 lbs by the stamp on the back side of them, but couldn't find the max pressure rating.

Jayco told me 110 psi., HiSpec says it depends on the valve stem used because they've pretty much quit rating their wheels based on max psi, but they too confirmed that I'm good to go at 65 psi.

[paggy00271]

We just swapped our factory tires for a new set of the Goodyear Endurance. What a huge difference in the bounce from the sidewalks. Are heading on a 10 day trip after St Patrick's Day and will give a better review of them after. Load Rating was 2,200 and speed rating is "M" (81 mph) not that I would want to tow that fast.


2017 Hummingbird 17RK
2016 Dodge Durango

Sent from my iPhone using Tapatalk Pro

[01tundra]

Originally Posted by paggy00271

We just swapped our factory tires for a new set of the Goodyear Endurance. What a huge difference in the bounce from the sidewalks. Are heading on a 10 day trip after St Patrick's Day and will give a better review of them after. Load Rating was 2,200 and speed rating is "M" (81 mph) not that I would want to tow that fast.


2017 Hummingbird 17RK
2016 Dodge Durango

Sent from my iPhone using Tapatalk Pro

So those are 10-ply (E-rated) correct? What size did you go with?

Since we switched tires at about the same time and have the exact same TT we should be able to get a good head-to-head comparison of them.

[paggy00271]

Originally Posted by 01tundra

So those are 10-ply (E-rated) correct? What size did you go with?

Since we switched tires at about the same time and have the exact same TT we should be able to get a good head-to-head comparison of them.

They are pretty similar to the Maxxis you put on but I have 205 75/R14.

On the R14 tires they are "D" rated (8 ply). I don't have the Baja so I have the smaller tires. They are inflated to 65psi and are rated at 2040 lbs.


2017 Hummingbird 17RK
2016 Dodge Durango

Sent from my iPhone using Tapatalk Pro