Big tire bounce?
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Big tire bounce?
Hey,
Wondering if bigger tires cause more "bounce" than normal tires do. I just replaced the shocks on my 99 Ranger XLT extended cab, and while I do notice that the truck doesn't ping-pong across the road like it used to, it still seems to have a lot of "bounce" to it. It has 31x10.5R15 tires on it. Would they tend to "bounce" more than stock tires, all else being equal? Note: I have no plans to take this truck off-road, so if anybody has an idea how much a set of 4 ION 15x8 wheels with brand new (< 500 mi) 31x10.5 AT tires would bring, that'd be good info to have. Thanks.
Wondering if bigger tires cause more "bounce" than normal tires do. I just replaced the shocks on my 99 Ranger XLT extended cab, and while I do notice that the truck doesn't ping-pong across the road like it used to, it still seems to have a lot of "bounce" to it. It has 31x10.5R15 tires on it. Would they tend to "bounce" more than stock tires, all else being equal? Note: I have no plans to take this truck off-road, so if anybody has an idea how much a set of 4 ION 15x8 wheels with brand new (< 500 mi) 31x10.5 AT tires would bring, that'd be good info to have. Thanks.
Laughing Gas
Joined: Aug 2003
Posts: 1,175
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From: So. Cal.
Tires such as the 31x10.5R15 are sometimes called "ballon" tires, and yes, they will bounce more than a low profile tire. The bounce you get is part of the trade-off you pay for their increased shock absorption capability. A lot of bumps in the road are absorbed in the tire and never make it to the suspension.
Laughing Gas
Joined: Jun 2005
Posts: 820
Likes: 11
You might want to play with the air pressure. 31s are LT (light truck) tires compared to the Standard Load donuts that these trucks come with stock. They have stiffer sidewalls and act a little different. If you have too much air they won't flex enough riding on a light weight compact truck and will overwork the suspension. It would make worn shocks more noticeable if that is the case. If you're running too little air they could be flexing too much and basically acting like a spring without any damping. I just put 31s on my 98 and I’m still playing with it. Max pressure is 50psi but I’m running 35 now and I’m about to take it down to 30. Before you replace parts try the easy stuff first.
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Originally Posted by jokerforever
You might want to play with the air pressure. 31s are LT (light truck) tires compared to the Standard Load donuts that these trucks come with stock. They have stiffer sidewalls and act a little different. If you have too much air they won't flex enough riding on a light weight compact truck and will overwork the suspension. It would make worn shocks more noticeable if that is the case. If you're running too little air they could be flexing too much and basically acting like a spring without any damping. I just put 31s on my 98 and I’m still playing with it. Max pressure is 50psi but I’m running 35 now and I’m about to take it down to 30. Before you replace parts try the easy stuff first.
Somebody else had a tip about drawing a 1 inch chalk line across the tread and then driving over it to see where it wore first - edges or center. I may try that and get a definitive read on proper pressure.
The shocks that were on the truck were suprisingly not as worn as I thought they'd be (well, the rear ones weren't, anyway - the front shocks were in pretty bad shape). Replacing them did take care of some of the bounce, but maybe dropping the air pressure a bit will help, too. Thanks.
Post Fiend
Joined: Jan 2005
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I use to run my my 32's at 40 pounds with no bounce, I'ld say there's another problem unless it's your tire brand. I ran BFG's KO's.
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Elder User
Joined: Jul 2006
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From: Denver
The bigger tires will 'bounce' more than the stock ones for 2 major reasons:
1. The larger tires are heavier. The unsprung weight is one of the important factors in valving the shocks, and using tires/wheels that are significantly heavier than stock will result in the need for stiffer shocks to control the tires/wheels appropriately.
2. The tires act like a big spring. (Ever dropped an inflated tire from 2' off the floor?) The larger tires allow more deflection of the tire, which makes them 'bounce' more than the smaller tires. This also results in the need for stiffer shocks.
You mentioned that you just replaced the shocks. In my experience, many aftermarket shocks are not particularly good, even from the 'big-name' companies. My bet is you need better (stiffer) shocks.
1. The larger tires are heavier. The unsprung weight is one of the important factors in valving the shocks, and using tires/wheels that are significantly heavier than stock will result in the need for stiffer shocks to control the tires/wheels appropriately.
2. The tires act like a big spring. (Ever dropped an inflated tire from 2' off the floor?) The larger tires allow more deflection of the tire, which makes them 'bounce' more than the smaller tires. This also results in the need for stiffer shocks.
You mentioned that you just replaced the shocks. In my experience, many aftermarket shocks are not particularly good, even from the 'big-name' companies. My bet is you need better (stiffer) shocks.
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Elder User
Joined: Mar 2004
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From: Houston
I am more inclined to think that some tires seem to bounce more than others. One of the very first thing I noticed many years ago when I went from an off brand 31x10.50x15 mud terrain type tire (for the record they were Wide Climbers) and bought my first set of BFG AT's - the first thing I noticed was how much smoother the BFG's were...didn't seem like I was going airborn over speed bumps in my works parking garage like I was with the Wide Climbers.....maybe it's just me but I would think the quality of the tire can have something to do with it as well -
Laughing Gas
Joined: Dec 2003
Posts: 1,062
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From: Ford, WA
Waves - I had that same brand on my 88..(in the front only).. they were horrible.. i had one get popped by a rock on a dirt road (out in the middle of nowhere).. the hole was right where the tread and sidewall meet.. the rubber is horribly thin in that area..will never use that brand again..BFG TA-KO's are awesome.. I had those on my 86 Bronco for a long time.. they even survived the accident that killed my bronco..(the front, right wheel was almost up under the passenger side floorboard)
Cargo Master
Joined: May 2001
Posts: 3,208
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My 2003 2 wd calls for 30 and if I run them any higher than that (which I do when I pull my 10 ft trailer) it gets squirrelly on bumpy / wash board roads. They are just to light in the butt for stiff tires. If I run between 28-30 psi no real issues. But anything less than 24 and they get shaky these are Dayton 225/70/15's
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Thanks for all the info, folks. I think I'm looking at a combination of tires that may be too big for the truck and too little weight in the rear end. I decided to drop the PSI in the tires to 30, which seemed to make some difference. Still will probably go ahead and try to find smaller rims/tires, tho. Driving that thing is a real beating.