2WD, 7.3L 350 EB- New Tires- Road Sway

Michisurfer · 02-25-2020, 08:01 AM

Hi Everyone,

After much debate on tires- ended up putting on the Cooper Discoverer HT3, LT265-75/R16- Load E
2000, 7.3L, 350 EB
The old tires were wore down completely and needed something for our Spring adventures in Michigan- lots of road time- not much off road. The local tire shop recommended these and after research they seemed like a good fit.

First time out- the van had extra play in the steering- road sway is the best way to describe it? Previous owner in 2018 had new: tie rods- inner and outer- new ball joints- upper and lower, adjusting sleeves, new disc rotors- front- both sides- replaced wheel bearings and seals. pins and pin-boots. Camber/Caster Bushings (front)

The van drove fine on the old tires. New tires it has a ton of play in the steering and hard to keep straight. Could this be a simple tire alignment issue? Any suggestions on upgrading the struts or shocks for an overall smoother ride? We have a couple big road trips planned this summer and as of now the ride sway is my number one issue to fix.

Thanks!

Saeth

carringb · 02-25-2020, 08:20 AM

What's your axle weights and tire tire pressure?

Since tires are the only variable that changed, I'd focus on these rather than throwing parts at the suspension.

Michisurfer · 02-25-2020, 09:03 AM

I'll look into both of these things- running standard pressure out the door from the tire shop- how does one find out axle weights?

carringb · 02-25-2020, 08:40 PM

What do you mean by "standard pressure"? I wouldn't count on every tire store to actually check the door placard.

Out here in OR, we just pull into any state truck-scale that isn't doing enforcement. They leave them on full-time. But in other states, you might have to pay for a weight at a CAT scale.

Also, some landscaping supply stores have scales.

**Gooseberry** · 02-26-2020, 08:43 PM

I’d say 65 to 70 on e rated you are good

REF · 02-27-2020, 05:20 AM

Think we’re all missing the point that these tires are not stock running gear, and that going by the placard’s tire pressure guide based on OEM tires would not give correct psi’s.
This could just be the common effects of running brand new tires, sometimes they feel like they wander when they grab onto the normal road wear grooves.
But.....
The new E rated Coopers have a max psi of 80, the original tires were probably a D rated tire with a max of 65 psi, so if the shop were to go by the placard numbers, you’d most likely be under inflated on the new tires.
Check your tire pressures, and make sure they are properly inflated based on the new tire max psi. Keep in mind, you don’t necessarily need to run them at max psi, especially on a lighter build out, that’s where the F/R axle weights would come in handy, but running them 15-20 lbs under max might be the reason why the van feels like it’s wandering. I’d also think a good starting point would be F-70psi R-75psi

rpoole · 03-01-2020, 10:32 AM

Thanks REF, new reader, not-so-mechanical with a similar question. The tires on my van aren't the ones from the placard.

Vanzila · 03-01-2020, 01:01 PM

Tire Pressure.. Likely they set it way to low.

Vanimal · 03-01-2020, 02:23 PM

A few points I have experienced switching from BFG A/T's. I recently replaced all my steering tie rods I try to stay as close to the removal as the instal, meaning I did not move the vehicle, measured everything spray painted the old parts so I could count threads before putting on the old adjuster collar. All was well. I bought new "E" rated tires (E is all I run) and I had some wondering. I rechecked all my parts did a tow in measurement added another 1/16" in, I adjusted my tire pressure and it all went away. I will be doing a new alignment profesional check soon as I want to check toe in. I did notice that I had dirt (dust) on my tire shoulders, meaning the tire was over inflated at the recommended pressure and at the pressure I ran my BFG's. Tire pressure is a huge factor and if you change tire brands you must find your sweet spot!Not all vehicles are the same, weight and weight disbursement are key factors!

Lilnuts2 · 03-02-2020, 09:34 AM

To the OP. bump your tire pressure to Coopers recommended max pressure (probably 80psi)

Drive your van with the intend of looking how the steering is working. If it is still not working how you like it, lower the pressure 5 to 10 psi and drive again. Keep repeating this process until you either fix the problem or determine it's just not going away. You have to make a point to do a dedicated test season to dial in your air pressure, much like a racing team. Don't try one pressure one day at 2 in the afternoon on a sunny day and the next session on Thursday morning when it's cloudy and cold. You want a constant testing environment.

If the problem is not solved with air pressure I would go back to the tire store and till them these tires just are not working for you, (it happens) tell them about how the van worked fine prior and about your testing session, and you want to try another tire.