Ask Motorhead

SHOULD I UPGRADE TO BIGGER TIRES?

Motorhead Mark Lester
3/14/2013

 

Dear Motorhead:

I have a question about upgrading tires. I have a 2013 Sportsman 850 XP with EPS and want to upgrade to beefier 28-inch Maxxis Zilla tires. After doing some research I found that the 28-inch Zilla is lighter than any 27-inch equivalent.

Which tire would put less strain on my drivetrain and EPS system? The lighter, but bigger Zilla or a smaller but heavier equivalent tire?

Thanks,

Geoff B



Geoff!

Thanks for your email!

You've asked a really good question and one that might be difficult to answer.

Here's the deal - when you increase the OD of an ATV tire/wheel combo you work the ATV tranny (in this case a CVT) harder. You have effectively changed the gear ratio and will labour (and create increased heat) the tranny on low speed slogging and at engagement RPM. This can be countered by using low range whenever you're slogging and running at or near engagement.

You also increase the leverage the tire has over the tie rods and associated steering gear including the EPS system. In the case of EPS when you increase the leverage (forget about the weight for a minute) the EPS system has the opportunity to apply more force to the tie rods and tie rod ends when you're axle deep in mud or just hitting rocks that would deflect the wheels.

It's about the distance from the tie rod end on the spindle to the outside edge of the tire. So, can an EPS system and the associated steering gear take this extra leverage? My thinking is this - yes, but only to a point.

My suspicion is the steering gear will "take it" but it will wear more and faster. Depending on how abusive your riding is the wear may be negligible or may be extreme.

Your other question about tire weight is intriguing. The less a tire and wheel weigh the less strain there is on the shocks and suspension components like a-arm bushings, ball joints etc. However, this may be negligible as well.

For sure your ATV will ride better with lighter tires and wheels but if those tires and wheels are higher pressure, harder sidewall (6 ply) or otherwise aggressive mud meats ride quality will be deteriorated regardless of tire weight.

Like I said - a good question but difficult to answer.

Hope this helps,

Motorhead Mark




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