strange vibration only down steep hill 75+ mph

[joe diffy]

hi eric and members. i had a question. I have a 2009 honda fit (manul trans) with about 57000 miles on it. since i’ve owned it i’ve never changed the tires. I recently changed JUST the front tires with brand new tires and some used rims i bought. I mounted them myself and balanced them with a bubble balancer. I took it out on the road and drove up to 80 mph and didn’t notice any vibrations other than the engine and road surface. however i noticed under a particular circumstance there was a vibration. when i drove down a very steep hill at about 75 mph i noticed a vibration in the steering wheel. i found this very odd because on level roads and uphill i can go up to 80 mph with no vibrations. i put the old wheels and tires back on the front and did not notice the vibrations when driving down the same steep hill at 75 mph. what could this be? could it be the fact that i have old tires on the back and new tires on the front? could it have something to do with the used rims i bought and put on the front? I probably will eventually change the rear tires as well and hopefully the vibration goes away but i’m afraid it might not. if it helps the old tires are 175/65 -R15 84s and the new tires are 175/65 -R15 84t. really confused on what this could be. i also realize that getting it professionally balanced would probably be a good thing to try but i am a hard core do it yourselfer and would prefer not to. plus if it were a balancing issue wouldn’t it vibrate under all conditions and not just down hill? also what’s even weirder is the down hill it vibrated on was VERY steep. other downhills that weren’t so steep it did not vibrate.

Topic

[Dwayne]

I’m not saying your tires are the problem, could be lots of things causing the issue you have, but here is a good read

The definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. In English, that would translate to…A balanced tire is when the mass of the tire, when mounted on its wheel and the car’s axle, is uniformly distributed around the axle. Even easier yet, how about…there are no heavy spots.

Balanced tires can be the difference between a good or bad driving experience. Some cars (and drivers) are more sensitive to an out of balance tire than others, but no one is happy with a vibration.

An out of balance tire can adversely affect ride quality, shorten the life of your tires, bearings, shocks and other suspension components. If you have a vibration that is dependent on speed, and usually becomes noticeable around 40-45 mph and increases as your speed increases, it’s probably balance related. The other primary cause of vibrations is that the tire and wheel assembly isn’t perfectly round. Face it, if we go out far enough past the decimal point, nothing is perfectly round. This includes your wheels and tires. The problem is when the high spot on the tire, and the high spot on the wheel end up being matched to each other. This effectively doubles the amount of “hop” or runout. If re-balancing doesn’t cure the vibration problem, have your professional installer check the runout of the tire. If there is a “hop”, many times the problem can be fixed by simply rotating the tire on the wheel slightly. The technician should loosen the tire on the wheel, and turn it 180 degrees, and reinflate the tire after relubricating the bead. The runout should be significantly reduced or eliminated, and if it’s not, try it again, but this time rotate only 90 degrees, and if that doesn’t work, try 180 degrees on the third try. Done this way, the high spot on the tire has been tried at each quarter of the wheel. At one of those points, the tire should be good and round. At that point, rebalance the tire, and go for a test drive. If the vibration persists, the problem is either in the tire, or elsewhere in the vehicle.

[Lorrin Barth]

[quote=”lovetowrenchit” post=112675][quote=”joediffy345″ post=112673]thanx for the reply

First –
by set the tire you mean balance? i’m pretty sure i mounted and inflated the tires correctly on the rims so it’s hard to think what else could be wrong other than the balance.

Second –
for the second point this whole problem may never even come up in my daily driving seeing as how i probably won’t be driving down steep hills at 75+ mph any way. i think the speed limit on the hill was about 65 mph so i may have been speeding a little to test it out. luckily no cops were around. is the speed limit for most very steep downhills in america below 75 mph? this vibrating condition may not ever occur without speeding.[/quote]
stay under 65 and don’t worry about it:)I also pasted a really good link for you to read…[/quote]

Yeah, going down a steep hill at 75 mph – that doesn’t sound like a good idea in any vehicle.

[Erin]

If you are trying to save money – it doesn’t cost much to have the wheels professionally balanced. Probably less than what some of us spend each week on vending machines at work.
Just go to a good shop like discount tire and not some backwoods shop.

And by “set” the tires, yeah just proper mount and balance. ALSO – is there a chance the tires are those stupid unidirectional tires that are suppose to rotate a certain way? Maybe it is backwards?

DIY is fine with most things but tires is just something best left to a shop. If you had to pay yourself for the hassle, it would cost more than what a shop would ask.

[joe diffy]

a little update on my adventures in tire vibrations.

I don’t want to declare victory too soon BUT I think i’ve solved the problem. I put the two new tires/rims on the drivers side of the car and put the old tires back on the passenger side. The reason why i did this is to see if the odd combination of a new tire on the front and old on the back was causing the vibration down the steep hill at 75+ mph. I shot down the same steep hill at about 80 mph and….no vibrations. I couldn’t believe it, so i turned around and went down it again…no vibrations. To me this says that it indeed was a tread/grip issue. however one thing that i failed to mention was that the steep hill i drove down was paved recently and was very smooth. i could tell this by the fact that the ass-fault was jet black and road noise was minimal when compared to the other parts of the road.

so anyone out there who just replaces their front tires and experiences this same exact thing take note.

on a side note i am very impressed with the bubble balancer i used to balance these tires. (note: getting bubble balancers to work tho can be tricky) It may not be as accurate as a computer balancer but it did the job for speeds up to 80 mph and given that the speed limit for the fastest road in america is 85 mph (it’s in texas I believe) i highly doubt i will need more precision.

thanks for all your help and unless i post in here again assume it all worked out

[EricTheCarGuy]

That sounds like progress. First, tire balance issues show up in the 55-60mph range. The reason for this is something called resonance. It’s a term in physics that describes when a rotating object reaches a certain speed and causes a vibration. That said, I suspected your problem was the wheels or tires all along, especially since you put the old tires on and everything was fine. Honda’s are very sensitive to the tires you put on them. Cheap tires are not the way to go.

Also, your tire pressures are too high. Should be down around 32psi as suggested.

More info on solving vibrations here.

http://www.ericthecarguy.com/faq/determining-the-causes-of-vehicle-vibrations

Keep us posted with any updates.

[Author]

Replies