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Discussion Starter #1
Going from 190 tire to 180..how much gear to add??


Hello all,

switching from a 190 50 P1 to a 180 55 P1. I was happy with my gear and i know with making this move the 180 tire is actually taller. How many teeth do i need to add to the rear to get back where i was with the 190?? Ive read 2-3 will get you close...sound right?? thanks in advance. fyi they are mounted on a set of pvm 10y's rear is 6" i believe
 

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Shorty's Performance
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The 180 has a lot less contact patch than the 190 and you will have traction issues unless you're over 200lbs
 

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The 180 has a lot less contact patch than the 190 and you will have traction issues unless you're over 200lbs
:+1: if you got a 180/50 it would be a different story somewhat. I would stay with the 190. and the height difference will probably be about 1 tooth, 2 tops.
 

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REPOST Enforcement Mod
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Well, I'm not a drag guy, so I don't know how this would apply, but....

The 180 is designed for a 5.5" rim, so sticking it on a 6" rim would flatten the profile out quite a bit and increase the contact patch from its original design. So I'm not sure if traction would be affected all that much. But the 180 tire will be lighter weight, so it should help spin up faster than the heavier 190. In practice, I'm not sure how it would get you down the track, but I do see why someone would want to try it. As Op said, the height difference should work out to about adding a tooth on the rear, if at all.

Www.gearingcommander.com should get you closer to what you need to know.
 

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Using Skydorks train of thought though, being that it is going on a 6" rim instead of the designed 5.5, seems to me that although normally taller, being spread out wider may make it close to the same height as the 190/50.
 

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Gen2 Ripper
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No, spreading the smaller tire to fit s wider rim shortens it.
 

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Also remember the sidewall height is a percentage, 180 /55= your sidewall is 55% of 180mm. So I get 99 mm for the 180 and 90 mm for the 190, imo I think the 180/55 would still be taller on the rim. Now I was always told the reason for going to a 180 was for weight mostly. I also can not see how a 180 could have a lot less contact patch when at 15 to 18 psi, it not like we're using the whole tire anyway. So can you elaborate Madness?

BTW I'd say a tooth or 2
 

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i to did this swap to save on weight... when i was runnin a 190 i was -1 +2 but when i switch to a 180 to get the gearing back like i wanted i went up +2 and it was perfect... so i say +2 should get you back to where you want if you make the switch.
 

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Discussion Starter #10
My reasoning, is the 180 will give me a wider contact patch and save some rotational weight. I drag race only the bike will never see the street. Dont think i will have traction issues with a p1. Its fairly common, in drag racing to make this move. If it is i have a 190 p1, on the street bike that i can swap out.
 

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Discussion Starter #11
i to did this swap to save on weight... when i was runnin a 190 i was -1 +2 but when i switch to a 180 to get the gearing back like i wanted i went up +2 and it was perfect... so i say +2 should get you back to where you want if you make the switch.
exactly the answer i was looking for...thanks:thumbsup:
 

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Huh... I just mounted a 200/60 SC2 to reduce wheelspin at lean.

Good luck with that 180. :wink:
 

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Discussion Starter #13
Well, I'm not a drag guy, so I don't know how this would apply, but....

The 180 is designed for a 5.5" rim, so sticking it on a 6" rim would flatten the profile out quite a bit and increase the contact patch from its original design. So I'm not sure if traction would be affected all that much. But the 180 tire will be lighter weight, so it should help spin up faster than the heavier 190. In practice, I'm not sure how it would get you down the track, but I do see why someone would want to try it. As Op said, the height difference should work out to about adding a tooth on the rear, if at all.

Www.gearingcommander.com should get you closer to what you need to know.
:thumbsup:
 

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My reasoning, is the 180 will give me a wider contact patch and save some rotational weight. I drag race only the bike will never see the street. Dont think i will have traction issues with a p1. Its fairly common, in drag racing to make this move. If it is i have a 190 p1, on the street bike that i can swap out.
You learn something new everyday.:thumbsup::thumbsup:
 

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drag bike ..straight line!!...only time it will lean is turning on to the return road:lol:
Ah... well that actually makes sense. Reading fail on my part.

Gotta tune for your intended purpose, I suppose. :mrgreen:

Good luck man. Post up if you see a measurable improvement from that 180.
 

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so hows the 180 workin compared to the 190? Im curious about this because Im about to order a hook-up for my spare rim, and might order a 180 instead
 

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no problem you'll like the switch :eek:ccasion1
Is it really that much better? Im gonna order a shinko tomorrow and am trying to decide on which one.

I would rather choose 190 , I feel it's better.
could you elaborate more? just curious to hear the reasoning behind it.
 
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