Need help with Tires.

JumpJ

Adventurer
If anyone will know what to do you all will. I have a 2003 Ford Excursion. When we got it the tires were run down. I listened to a couple of mechanics who sold me on a Michelin LT 275/65/ R20 - we have 20 inch wheels:mad:. The truck has a 6 inch lift. Probably a bit too high but we crossed a river the other day without fear. The truck otherwise is great. HOWEVER, and a big HOWEVER, it wanders when driving down the highway and it did not do this when we had the tires on it that came with the truck(they were wider). I have consulted four shops and they all say the same thing. Go with a wider tire.

Suggested to me were BF Goodrich 325/60/20 either all terrain or mud KM2.

Another suggestion was to go to a 17 inch wheel.

This truck will not be a daily driver rather than a specific adventure mobile when finished. We will travel on both dirt roads and totally off road but no rock climbing.

Suggestions on tire make, size, wheel size or delivery to a live fire range for target practise welcome.

I'm sure I maybe opening up a multi thread question but would love to hear your thoughts on this issue. Thanks in advance. Will
 

The Adam Blaster

Expedition Leader
Going down to a 17" rim would be a good idea.
A 305/70R17 would be VERY close to the same diameter as your 20's that you're running now. A 315/70R17 would of course be slightly wider and taller.

Checking through the various other distributors I deal with, the 315 seems to be a much more popular size. (At least for the western Canadian market.)

20" tires are a fair bit more money than a 17" or even 18", plus they still aren't that plentiful in a lot of tire shops yet.

I'm very curious why you're getting suggestion to go to a wider tire to prevent the wandering issue... Fatter tire = more contact with the pavement = more chance that issues with your steering will be amplified = wandering would likely get worse.
I'd think you need an alignment, and those older tires wore in with the steering, and putting ANYTHING new on the rims is going to get your truck wandering a bit.

Take it to a shop that specializes in front end work and get them to take a look.
 

JumpJ

Adventurer
Blaster-I have gone to two alignment shops who say everythintg is tight. They claim think o fthe lift like a pyramid. A thinner tire underneath is going to cause the weight and height to wander. Apreciate the input-Thank You.
 

sasaholic

Adventurer
totally false. a wider tire wanders considerably more than a skinny tire. ive delbt with this first hand. tire design also lends a hand in wandering a great deal, but its usually a problem with more aggressive tread patterns. that said my 35 12.5 15 km2's dont wander to bad for what they are.
 

78Bronco

Explorer
A wider tire is more prone to follow the variations in the road more than a narrow tire of the same diameter. The changes in road crown or troughs worn into the pavement effect the suspension geometry thus changing the handling characteristics. A tire with a higher sidewall could cause the vehicle to wander more than a low profile tire but how many of us are running a higher sidewall tire without these issues. Also, consider that the factory steering components were designed to work with a 31" tire and now you have 36" tires which it might not be able to handle.

What handling behaviours is the vehicle having? Is it pulling to one side then pulling to the other or is it just pulling in one direction? Does the vehicle pull to one side under hard braking? Could be an air pressure issue. Wheel bearings, ball joints, mounts flexing from additional leverage, how is the castor angle, any death wobble?
 

cocco78

Adventurer
Are your new tires the same load rating as your old ones? If your old ones had a higher load rating than your new ones you could be feeling that difference in sidewall strength? Actually sidewall strength can very from tire brand to tire brand even with the same load rating.
 

IdaSHO

IDACAMPER
What tire pressures are you running front and rear?

I find that running a slightly LOWER than recommended on the front dramatically improves road feel through the tires, and reduces wonder.
 

redthies

Renaissance Redneck
Since most people are talking about wander and pressure, I will toss my hat in the ring on size and type of tire. I totally agree with the previous poster (Adam?) that 17" rims are the way to go. There are many more choices for size and brand in 17. They are also WAY cheaper! You said this wasn't going to be a daily driver, and seeing as it is an Excursion (diesel?) you will want something that will take the weight. Toyo MTs in a 35 or 37 would be my choice.
 

JumpJ

Adventurer
First off thanks for the input from all. The truck will not stay put. It is not huge correction taking place but constant correction to keep it straight and in the lane. Three experts have driven it and said same thing but have various ideas for fix. Lower the lift and go with smaller wheel, which is expensive and while 6 is a bit high this defeats the purpose. Wider tire was suggested by two of the three. The Michelins are E rated. Looks like I should start with going from a 20 inch wheel to a 17inch and trying that first. Looks like the live fre range maybe the answer.
 

Redline

Likes to Drive and Ride
Like the others, I suggest going to a shorter wheel. Won't a 2003 accept a 16" wheel? If so I would recommend a 16", lots of tire choice and less expensive. If not, then 17-18" wheels.

While I prefer as much sidewall as possible (shorter wheels) you might consider the relatively narrow but tall 285/75R18 size.

Make sure you have enough caster correction for that six inch lift, a possible reason for the wandering/tracking issues.
 

bronconut

Observer
Like the others, I suggest going to a shorter wheel. Won't a 2003 accept a 16" wheel? If so I would recommend a 16", lots of tire choice and less expensive. If not, then 17-18" wheels.

While I prefer as much sidewall as possible (shorter wheels) you might consider the relatively narrow but tall 285/75R18 size.

Make sure you have enough caster correction for that six inch lift, a possible reason for the wandering/tracking issues.

X2 on the caster do you have a print out from the alignments? I consider steering stabilizers a band aid but having one might help with your lift also. Do you have any bump steer due to the lift?
 

JumpJ

Adventurer
No bump steer but a thrid alignment shop found a ball joint issue and is a friend of my Land Rover mechanic so the beats is going in tomorrow for new ball joints at 134,000 miles he says he thinks that this is the issue. Fingers crossed on that one. And thanks again for the input and suggestions.
 

DT75FLH

Adventurer
ball joints will do it. but if you still have it after I'm leaning toward not enough caster after the lift was put on...

my jeep did it till the caster was adj....took a few times to get it right and after it would track straight even at 75-80 mph.

some shop SUCK at diagnosing....I wouldn't want to mention (cough cough 4wp in LV)

some shops just put lifts on then blame everything on worn out component's.

my .03
 

JumpJ

Adventurer
Break Open the champagne-it was the ball joints. Wallace came back this afternoon. Drove like a Rolls Royce. Mounted the RTT tonight and preparing for the weekend.
THANK YOU TO ALL FOR YOUR INPUT AND ADVICE. ONCE AGAIN FULL SIZE EXPO FORUM MEMBERS ANSWER THE CALL.
 

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