It wasn't until I moved from deserts of California to the mountains of Utah (where mud and snow is rather more prevalent in our riding than dry sand ;-) that I realized some of the problems associated with wheels with an increased negative offset (Need help with what 'offset is? See the explanation at the end of this blog). The first thing I noticed was how dirty I was after even a short ride. I compared that to tires that resided properly under the fenders - something I've realized were properly named 'fenders'!
The other thing I found out about wheels with more (negative) offset is their effect on the handling of the machine. The greater the offset of the wheel to the outside of the machine, the more effect it has on the suspension and steering. Add to that the fact that this happens because you've most likely added heavier, aftermarket tires and wheels farther out and you have not only increased the amount of unsprung weight, but you've also increased it's leverage. Because of that, the tires have a far greater effect on the ATV (or UTV) whether it's the wheel and tire's movement downward from dropping down into a rut or reacting upward to a rock or other bump. The greater the mass and the greater the leverage, the greater effect it will have. And that's not a 'good' effect.
An even more noticeable effect of increased negative offset is what it does to the steering. That same leverage we mentioned above, when combined with a tire with more traction will now far more easily overpower the steering leverage you have. First, the steering is far more 'grabby' with increased negative offset than with the same aggressive tread with a more positive offset. Then, the more traction and the added leverage can (and often will) be able to out-wrestle you for control of the handlebars or steering wheel.
Yet another effect of this added offset and added traction is its ability to also overpower a differential. A 'limited slip' front differential will be far less effective and unable to 'lock in' when the amount of leverage and traction is changed.
And it goes without saying that the effects of all this weight and leverage will add tremendously to the wear and even breakage of all the suspension, brake, and drive components.
So, what's my point? Simply this - It's easy to look at a set of very aggressive tires mounted on a set of wheels sticking out past the fenders and go, "Wow, that's cool-looking. It must work awesome" and be overpowered by the appearance of performance. But real performance is not measured by looks, perception, or (imagine this) popularity, but by actual performance. Yes I know, that's a profound statement and you may need some time to let it sink in. What's even more amazing is that this same perception of performance applies to other areas of an ATV as well, but we're not talking about swingaxle's versus IRS systems here ;-)
I've indeed been very fortunate to be able to try an incredible variety of wheel and tire combinations on a huge assortment of machines and most recently in a great many different trail conditions. And I've learned a lot....
Negative offset may look good and add some much-needed stability to some ATVs, but is offset (no pun intended;-) by a detriment in steering precision, handling, and even traction.
Big, giant tread may also look good but may come with the penalty of added weight, lack of steering precision (and control) and even a loss of traction and definitely a loss of power.
The general rule that seems to 'almost' always work is the use of three basic principles; Use the stock aluminum wheel or an aftermarket aluminum wheel with the exact same offset as the stock wheel. Find a moderately aggressive tire and then always choose the one with less over more. And finally watch the weight - it's easy for tires to be incredibly overweight in the name of traction and reliability.
And actually when you apply all three of those principles you'll find the choices are narrowed enough that your decision is easier.
Oh, did I mention that no matter what it needs to be radial construction?
All of this is knowing that no one modification to your ATV will have a bigger effect - good or bad.
OFFSET EXPLAINED -
The offset of a vehicle's wheel is the distance between the centerline of the wheel and the plane of the hub-mounting surface of the wheel. It can thus be either positive or negative. Offset has a significant effect on many elements of a vehicle's suspension, including the suspension geometry, clearance between the tire and suspension elements, the scrub radius of the steering system, and the width of the wheel faces relative to the fender coverage.
Zero Offset - The plane of the hub mounting surface is even with the centerline of the wheel.
Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the outside of the wheel. Positive offset wheels have most of the wheel toward the inside of the wheel.
Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.
Positive Offset - The plane of the hub mounting surface is shifted from the centerline toward the outside of the wheel. Positive offset wheels have most of the wheel toward the inside of the wheel.
Negative Offset - The plane of the hub mounting surface is toward the back or brake side of the wheel's centerline.
D
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Brilliant comments!!! If only all those morons with 15" wheels, wheel spacers, nerf bars, and 100 lbs of stereo equipment on their side x side's read this! Then again, even if they did, they'd be too stubborn and stupid to believe it.
ReplyDeleteIf they were reading this they probably wouldn't be such 'morons' ;-)
ReplyDeleteDoug
ReplyDeleteFinally someone is discussing after-market wheels that effect the performance, handling and safety of ATV machines; you didn’t mention safety, but it was implied (my take).
I have a 07 KingQuad 700 and I made the mistake by installing after-market wheels and tires; here is my setup: I purchased ITP SS112 (14”) wheels, nice looking it really made my quad look more impressive and the tires were ITP Terracross (26” tires), a great tire by the way. OK let me describe my first trip out with the ITP wheels. The quad was more skittish on the trials as the quad would wonder especially when traversing ruts on the trail, I found more effort required to maintain control of the quad, also at one point the handle bars were jerked out of my hands and the quad crashed into some brush (certainly was a wakeup call).
The performance of the quad diminished as the power was reduced by the larger and wider wheels and tires, not to mention the fuel consumption increased. Normally I would get around 33 MPG (miles per gallon) and with the ITP setup the mileage dropped to 27 MPG, no improvement there.
After a few more trips out I decided to sell the tires and wheels and reload my stock wheels with Terracross tires (25” standard size for the quad). Mileage jumped back up to 33 MPG, but more importantly the ride and handling improved, so what does that mean to me; I feel more confident and secure on my quad with the standard wheels and Terracross tires.
This experience was rather costly to me as the ITP wheel and tires are very expensive and when I sold then as used, I lost half the value of new. I wanted to share my experience so other readers would avoid the mistake I made.
Jeff
Great story Jeff! I have learned that lesson more than once but thankfully never with my own money spent on the wheels and tires, and never ending in a crash - but close enough it scared me bad!
ReplyDeleteAnd I didn't think about MPG. Thanks for that info.
DE I can agree with you on the offset of aftermarket wheels and the weight of the larger tires.It also makes a difference in steering effort.
ReplyDeleteI've butted heads with some of the wheel and tire manufacturers over this and they come back with, "They look good and they sell!"
ReplyDeleteCheck out Jeff's story above. Not sure if it was him or another guy that weighed the 14" ITP wheels against the stock and they were just over 14 lbs compared to just over 6 lbs! Yikes!
That's one of the big worries I have with this tire test we have coming up using the Polaris XPs as they run 14" wheels. Should be an adventure;-)
When I got my skat Track extremes sand tires I payed big bucks for a set Douglas .190 red label wheels. They weigh 21 lb thats a 25"X10"X12 Paddles with 10 paddels and a wheel. They works well it climbs Coke Cherry at St. Anthony dunes. Maybe the high dollar wheels are worth it.
ReplyDeleteAs Colin Chapman said, "add less weight every place you can!" And I say unsprung weight is the best place to add 'less weight' any time you can. They spin up faster, stop quicker, and handle better.
ReplyDelete