Tires or a transfer case?

[berndog24]

I have a 2000 Ford Expy XLT AWD. Recently I went on a trip into the central Arizona mountains towing my Kawasaki Teryx. I had been hearing quite a bit of rumble from the front end that I now know was a bad tire as my friend pointed out when I arrived. I bought 2 new tires and the rumble was gone. Unfortunately now it makes a howling kind of sound when accelerating. I towed my toy about 175 miles home in 100+ degrees with no problems other than the noise. I'm pretty sure (but not positive) that noise was not present before the new tires went on. I'm thinking it's because I didn't get 4 new tires. The new ones are the same size but they are not the same brand. I read in another forum that something like this ocassionally happens when installing the spare.I don't want to throw money at 2 more new tires if I need to put it into a transfer case. Also don't want to put it into a TC if it's tires. I'm leaning towards tires since I never noticed the howl before purchasing the new front tires. Any thoughts on this or has anyone experienced this? Thanks ahead of time for any info anyone posts here.

 

[FordandPolaris]

Could be the different tread pattern. Different tires will "howl" depending on the pattern.

 

[berndog24]

Well, what I read on this other forum was that if the tires are slightly different diameter it tricks the computer into thinking there's tire spin and kicks in the 4wd intermittently. I haven't heard of this but my experience with AWD and 4wd are basically nill so I'm looking at every possibility. I should add that this howl is only under a load and goes away on steady throttle. There is no slipping as far as I can tell so I'm not thinking it's a transmission issue. I'm pretty sure this started when I replaced the front tires.

 

[bedrck46]

Just a thought but have you tried switching the fronts to the rear and the rears to the front to see if the howl sounds like it has changed any

 

[KWT2000]

explorers use a viscous coupler in there awd system where the expeditions dont so i doubt it is the t case,

what brand and type of tires did you put on and what did you take off