Towing instability with new OE Firestone 20"

[SpectatorRacing]

I have been towing my ~11,000 tag trailer since 2010 when I bought my 2500 RAM truck, using the stock 17" BFG tires. The trailer pulls like a dream up to speeds over 80 mph in just about any weather condition. This is why I bought a RAM

I recently bought a set of 2014 takeoff 20" rims with the OE Firestone Transforce AT 285/60/R20 tires mounted (nearly new tread in rear, about 1/2 worn front). I have towed three times since this change and the trailer is unstable and induces sway at speeds as low as 60 mph. I have verified tire pressures in both the truck and trailer, changed loading in the trailer, etc but nothing improves towing.

Has anyone else towed a 10,000+ load with the new tires? What's going on? Do i have to go back to 17" or is it a matter of the tire and not the wheel size?

 

[Mingoglia]

I've found new tires have tread squirm which mostly goes away after several hundred miles. May want to give it some time on those rears.

 

[MRinehart]

was wondering where you got the takeoffs and what was the price.

 

[Alan Reagan]

Did the 20" lift the front of the trailer making the tongue weight change (shifting weight to the rear)? My truck came with the 18" Firestones and it tows fine.

 

[Jim W]

I have been towing my ~11,000 tag trailer since 2010 when I bought my 2500 RAM truck, using the stock 17" BFG tires. The trailer pulls like a dream up to speeds over 80 mph in just about any weather condition. This is why I bought a RAM

I recently bought a set of 2014 takeoff 20" rims with the OE Firestone Transforce AT 285/60/R20 tires mounted (nearly new tread in rear, about 1/2 worn front). I have towed three times since this change and the trailer is unstable and induces sway at speeds as low as 60 mph. I have verified tire pressures in both the truck and trailer, changed loading in the trailer, etc but nothing improves towing.

Has anyone else towed a 10,000+ load with the new tires? What's going on? Do i have to go back to 17" or is it a matter of the tire and not the wheel size?

Why did you go with the 20" tire?

If you were looking for improve load carrying ability you could have stayed in the 17" or go to a 18 inch size tire. I choose to stay with 17" tires but I am using a Nitto Dura Grappler LT285/70/17E 126R rated tire with appropriate rims for the these 10 ply tires.

Jim W.

 

[Joseph Donnelly]

Try moving the front tires to the rear, and rears to front; see if that helps. If so, replace the tires if still not good. And, as above, make sure the trailer sits level.

 

[SpectatorRacing]

I switched because the truck needed new tires and these 20's fell into my lap for a good price. And they look much better, IMO the tiny 17's look ridiculous under this truck.

I am starting to think it is the trailer level, thanks for the suggestion. The truck definitely sits higher unloaded than it did. I will hook up again and check it. Perhaps I just need a lower profile sidewall to fix the issue.

Thanks to all!

 

[Alan Reagan]

Do you have any way to lower the front of the trailer? I'm assuming this is not a gooseneck, just a receiver hitch. If the trailer is not level and you have a lot of weight on the rear, it will fishtail on you. I finally broke down and bought an adjustable receiver hitch and it really has made a difference in towing. With my fixed hitch, I could never level the trailer. It made for a rough ride. Leveling made a lot of difference in the ride and stability.

 

[SnoKing]

Tell us more about the trailer! Hope it does not have ST tires at those speeds!

From JIMMY SOUL lyrics "If you wanna be happy for the rest of your life. Never make a pretty woman your wife. So for my personal point of view. Get an ugly girl to marry you. If you wanna ..."

Pretty 20's vs ugly Eighteens or Seventeens!

SNOKING

 

[slick rock steve]

^^^^^^^
See the above!

 

[AH64ID]

The tires you installed are 1.5" taller on the rolling diameter. That will place your hitch 3/4" higher, have you compensated for that?

Also your speedo will be 5% off if you haven't corrected for it.

Why did you go with the 20" tire?

If you were looking for improve load carrying ability you could have stayed in the 17" or go to a 18 inch size tire. I choose to stay with 17" tires but I am using a Nitto Dura Grappler LT285/70/17E 126R rated tire with appropriate rims for the these 10 ply tires.

Jim W.

Very few 17's have a load rating higher than 121, and it's becoming fewer each day. Several tires that where 126-128 are no longer and I expect the Nitto's to follow suit shortly. There is some federal reg about 17's being limited to 121.

My brother has Dynapro ATM's on his truck in 285/70R17. They where 126 when he bought them and a year later one needed replacement for road hazard. The new one is 121.

Toyo AT's in 285/70R17 where 126, and now the AT II's are 121.

The new Nitto G2's all dropped to 121, where the original Terra Grapplers went to 126.

I would expect the Dura Grapplers to drop to 121 anytime.


The 20's the OP has carry the same rating as the OEM 18's, 3640 @ 80.

It could be the fact that they are taller and changed to vehicle profile, or just a softer rubber compared to the LRE's he had with the 17's.

I seem to recall reading about other stability issues with the OEM 20s thou.. which makes me think it's specific to the Firestones.