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This is my first ever forum posts so please bear with me... I have a 2019 Polaris sportsman 850 SP and I wanna upgrade the tires. I’m looking at 29’s but I don’t know if they will fit if I keep the suspension and control arms stock. I would not mind trimming some plastic but I don’t want to do any aftermarket suspension work. Does anyone know how big I can go?
 

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29s will fit with some floor board trimming.
 

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28’s will fit with no mods. 29’s will fit but rub under load and some fender trimming may be necessary. You won’t need to trim the floor boards, just the fenders.
 

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28’s will fit with no mods. 29’s will fit but rub under load and some fender trimming may be necessary. You won’t need to trim the floor boards, just the fenders.
Oooo that’s very intriguing! What if I tighten up the shock adjusters a couple clicks? Maybe that’ll keep the suspension tight enough that it won’t rub
 

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Yeah 28s are the sweet spot.
 

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Oooo that’s very intriguing! What if I tighten up the shock adjusters a couple clicks? Maybe that’ll keep the suspension tight enough that it won’t rub
No 29’s will still rub. If you get the Highlifter rear raked control arms you’ll be ok or a 2” bracket lift. You might also be ok with the Highlifter HD springs, those can get you up to 1” extra lift. As bp says, 28’s are the sweet spot and tbh 1” greater height In tires only gives you 1/2” additional clearance Which isn’t gonna make a difference.
 

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No 29’s will still rub. If you get the Highlifter rear raked control arms you’ll be ok or a 2” bracket lift. You might also be ok with the Highlifter HD springs, those can get you up to 1” extra lift. As bp says, 28’s are the sweet spot and tbh 1” greater height In tires only gives you 1/2” additional clearance Which isn’t gonna make a difference.
Wait I've been in particular situations where 1/2" makes a world of difference 😜🤣🤭!!!
 

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Wait I've been in particular situations where 1/2" makes a world of difference 😜🤣🤭!!!
That’s a different subject altogether. In that scenario every inch counts 😂
 
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But I guess it’s safe to say that I should stick with 28’s just to be sire. My stock tires are 26 inch so hopefully 1 inch all around is safe
 

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I’m running 28” mega mayhems on stock rims, no lift, stock axles and no issues. I’ve put on 29.5 OT 2’s for fun and they fit with some rubbing. If I were to run those all the time I’d definitely look at a lift and stronger axles.
 

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Thank you very much! I was hoping that somebody would actually have some personal experience with 29’s so I’m definitely going with the 28’s. I appreciate everyone’s help! Byerrrraaaasssspppp boys!!!!!
 

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Thank you very much! I was hoping that somebody would actually have some personal experience with 29’s so I’m definitely going with the 28’s. I appreciate everyone’s help! Byerrrraaaasssspppp boys!!!!!
I run 29" Maxxis Viprs. 100% stock. No rubbing or fitting.

You have to be careful by just going with tire size by the numbers. Each manufacture is different and even differ in size by the same manufacture.
28" Maxxis Bighorn Originals measure the same size as 29" Maxxis Vipers. I would say 28" measured with a tape measure is as big as you can go.

My 29 Vipers measure about 27.5

D
 

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Dude that’s fucked up. I can’t believe there’s that much of a difference in a tire that’s supposed to be 29 inches and only measures 27 1/2!? I mean I guess they figure if every company that makes pants can make up their own sizes then they can do the same with tires! Ha ha
 

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I run 29" Maxxis Viprs. 100% stock. No rubbing or fitting.

You have to be careful by just going with tire size by the numbers. Each manufacture is different and even differ in size by the same manufacture.
28" Maxxis Bighorn Originals measure the same size as 29" Maxxis Vipers. I would say 28" measured with a tape measure is as big as you can go.

My 29 Vipers measure about 27.5

D
Very good point Deucer. Just because a tire has 29 embossed on the side don't mean it actually measures 29" when mounted. Some tires actually measure 2-3" less than the advertised size.
 

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Is that because of different weights of ATVs and tire pressure? I can understand that the tire may be 29 inches inflated rockhard but 27 1/2 when you’re running 6 psi
 

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What I was told by my dealer: the tire size is measured at max PSI for tire. This causes a slight "balloon/rounded" tire where the peak is measured.
I have tires rated for 18psi, but they're under 10. When upped to 15, they're noticably taller/more round. (When viewed inline, not side profile.)
Rocktane XD's
 
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