Larger Tires Causing Od Rumble

[mi79]

About 5k miles ago I had some toyo open country 285/70 r17 tires put on. I'm really happy with the tires, no complaints there, but right away I did notice a rumble from the engine whenever the trans went into OD (only between 43 and 53 mph). The sound was pretty minor, not enough to worry about....just figured I should get the PCM updated for the larger tires. A couple of weeks ago I ended up having the trans rebuilt (unrelated issue, burnt clutches 'n such), and was hoping that the rumble may have been part of the trans symptoms...well, it wasn't. Now that the transmission is tight, OD locks up more firmly, still at 43mph, but it really makes the engine resonate or whatever. It locks up at 43mph only turning about 1200rpm. I don't know if these tires are that much heavier or what, but it's driving me nuts. The only way to avoid it is to keep my foot in it long enough to get past 53 or use tow/haul...

 

I took it into the dealer today and had them update the PCM for the tires, I notice a difference everywhere but OD....so should I look into a programmer to keep it from dropping into OD so early?

 

Thanks for any info.

'05 Avalanche 1500

~55k miles

[Tyler_LS1]

What engine? 5.3?

[mi79]

What engine? 5.3?

 

 

Yeah, and the engine runs perfectly, just seems like it's being worked kind of hard because of the trans or tires.

 

thanks.

[Ranger]

It may be the tires themselves, being a somewhat aggressive tread setup they do tend to have some highway vibrations. My BFG A/Ts have a slight bumpiness to them but I mainly attribute that to being a Load Range E tire.

[markw8]

Your larger tires have changed your overall axle ratio. 1200 rpm at lockup is low for that heavy Avalanche. Especially if your going up at all. You may be lugging slightly. Mark.

[mi79]

Your larger tires have changed your overall axle ratio. 1200 rpm at lockup is low for that heavy Avalanche. Especially if your going up at all. You may be lugging slightly. Mark.

 

Hey Mark, thanks for your response....it's kind of what I needed as a nudge to go for a programmer. The tech at the dealer mentioned the aggressive tread pattern too as a possibility, but these tires are surprisingly super smooth and quiet at all speeds. The 43-53 OD rumble is only noticeable under throttle (as in cruise or light acceleration)...if I let off the noise goes away, even if it's still locked up.

 

The more I listen to it the more it almost sounds like the downpipes or cats are resonating, which is def better than the engine making that sound... Either way, I think I'll go with programming it to lock up at like 50. Hopefully HP Tuners offers that option....I like how their product is software rather than a hand held.

 

Thanks again for all the responses.