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Discussion Starter · #1 ·
I've put a deposit on a new Ace 570 SP and just waiting on the dealership to get it in stock from Polaris. In the mean time i've been researching and reading a lot on these forums and other websites about tire sizing and weights. From what i've read it seems as though the Ace's have no clearance issues going to a 26 inch tire, and no modifications need to be made. Someone correct me if this is wrong. The main thing I want to know about is what is the power loss vs ground clearance lost/gain ratio between 25 inch tires and 26 inch tires. Being more specifically I'm looking at going with either BigHorns or Dirt Commanders.
 

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I put 26" Duro radial power grip tires on my Ace and the power loss was negligible and the ground clearance gain was noticeable. Added a 2" lift kit and now have an amazing amount of ground clearance. There was no interference with any suspension parts when I went up both in diameter and width. I highly recommend the 6 ply Duro Power Grip radial in the 26" size, very similar tread to the Big Horn and 20% cheaper.
 

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I actually put 27" Roctane tires on my Ace. I put 2" spacers otherwise the tires would rub the fender wells. We did several drag races up to about 45 mph and could not tell any difference in performance. I am sure there was some performance loss and there may have been some loss of top end speed but where I ride I have only opened the Ace all the way once.
 

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Discussion Starter · #4 ·
I actually put 27" Roctane tires on my Ace. I put 2" spacers otherwise the tires would rub the fender wells. We did several drag races up to about 45 mph and could not tell any difference in performance. I am sure there was some performance loss and there may have been some loss of top end speed but where I ride I have only opened the Ace all the way once.
When you say "we did several drag races" Is this your Ace vs an Ace on stock wheels and tires or ???
 

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I had two friends that had Aces. One had 26" Roctane tires and one had 26" Sedona Ripsaws. Here is a link to the thread that has photos of the Aces and discusses the drag races.There is a thread in the tires section titled a comparison of 26 inch and 27 inch tires that has photos and details.
 

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I had Maxxis Bighorn 25x8x12s all the way around on Polaris RZR wheels.
I temporarily (for a bit of street testing and for one ride on 4x4 trails) installed a set of Bighorn 26x9x12 all the way around.

When street testing, I could tell that my acceleration was "a little bit slower" (sorry, can't quantify that), and that my top speed was 2-3 MPH lower.
The difference was noticeable, but only because I had JUST swapped them out. Give me a week and I'd have forgotten was 25x8x12 was like.

I gained more ground clearance than I expected to. In theory, the difference between 25" and 26" tires should be exactly 1/2" (you only count what is below the hub).
But I think because the tires were wider, but on the same width wheels, that translated to the tire being taller.
I also had more pressure in the larger tires.

Here are my measurements:
The 25x8x12 BigHorns on 6" wheels at 5psi stand about 24.75" high.
The 26x9x12 BigHorns on 6" wheels at 7psi stand exactly 26" high.

They were in the air when I did the measurement though, no weight on them.

When I went for a ride at a 4x4 trail with the larger tires, it definitely felt like a smoother ride. I didn't strike as many rocks and roots and things.
I ended up going back to the 25x8x12s because I wanted to stay at or under 50", but if I did not have that constraint, I would go with 26" tires.
 

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Discussion Starter · #7 ·
Did any of y'all need to modify with spacers, aftermarket wheels, or anything else because of clearance issues when turning the front wheels? I thought I remembered reading somewhere that someone said their 26 inch Bighorns would rub when the front tires were turned all the way to one side or the other?
 

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With 26x9x12 Bighorns on Polaris 6" wheels with 4+2 offset, I did not experience any rubbing, either while turning or while on a sidehill.

It's all going to depend on the height/width of your tire, the width of your wheel, and the offset.
We could call out some specific setups which need spacers, and some which do not, but until you settle on a specific tire/wheel combination, there's no way to know.
Once you do decide on a specific setup, someone may be able to answer regarding whether you need spacers.

If you want to go with oversized (27", 28", or maybe even bigger) tires, and don't want spacers, you can look into Highlifter's curved control arms.
In addition to providing better ground clearance for the control arms, they also move the hub a couple inches forward, which prevents rubbing with larger tires.
 

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I have ITP SS112 wheels and 27" Roctane tires. I had to use spacers to keep the tire from rubbing in the front fender well. One-Shot had the same wheels and 26" Roctane tires. He also had to use 2" spacers to stop the wheel rub. Greybeard had Polaris wheels and 26" Ripsaws. The wheels had a different offset and he did not need spacers.

Scoundrel, I am curious if you measured the loss of top in speed with a GPS or with the speedometer. Because of the larger circumference of the 25" tires, the speedometer should register 48 MPH when the forward speed is actually 50 mph. If my math is correct, the 26" tires have a 4% larger circumference than the 25" tires.
 

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Scoundrel, I am curious if you measured the loss of top in speed with a GPS or with the speedometer. Because of the larger circumference of the 25" tires, the speedometer should register 48 MPH when the forward speed is actually 50 mph. If my math is correct, the 26" tires have a 4% larger circumference than the 25" tires.
That is a very good point, and I wish I could remember for sure. Lemme see if I made a note of that at the time...
Nope, I cannot find a post where I indicated that. I may not have posted it at the time. It could have gone either way.
But the difference in top end was not really worth making a big fuss about, as I never go that fast for more than a few seconds at a time on the trail anyway.

I guess you could say that if I have to record my speed carefully with a speedometer, and corroborate it with a GPS, then it's not a "real world difference". :drive1:
 

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Discussion Starter · #11 ·
After reading all of your replies and thinking, I didn't even ask if all this data y'all are giving me is on the Ace with the 320 cc engine or the 570 cc engine?
 

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From a chassis / fitment perspective, it does not matter because they are the same.
From a power loss / speed perspective, the 570 will do somewhat better than the 325.
I would be more comfortable with the idea of going to taller, heavier tires with a 570 if I had no width restrictions.
 

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Discussion Starter · #13 ·
Yeah I knew both machines are identical but what I wanted to know is all these tests you guys have been doing with tire sizes, are y'all doing it with the original Aces or the 570's?
 

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Discussion Starter · #15 ·
Ok I decided to go with the 26 inch Dirt Commanders. Now that I've gotten tires ordered, I just need my dealer to get my Ace in stock that I ordered so I can put them on and then have my buddy help me start designing a custom roll cage for it!
 
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