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195 Slick On 5.5 Inch Rim?


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I have been noticing that all of the guys here in Phoenix are running 190's and 195's on their 600's with the stock 5.5 inch rim. I have quite a few sets od very good Dunlop Ntec 195 rear and 125 fronts that I am contemplating trying out on my GSXR 750.

 

What I know= I know that the profile of the tire is going to change because its a wide tire on a skinny rim.

= I have heard that this will distort the tire and the enhanced contact patch will not really help if the tire is distorted.

= I know that the bike is going to handle heavier but the track I am using them on this weekend is a very fast track and is not technical

 

 

What I want to know= will the enhanced contact patch really help if it is on the 5.5 rim?

= what are some other issues that may arise because of this change.

 

 

Thanks in advance

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I just got home and looked at the profile and it is a 195/65 if that helps at all

 

I'll let Will know about this thread, but he's been traveling to Pocono, not sure if he'll have e-mail access soon.

 

Cobie

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I run 190/55 and like the feel. When I did switch from a 180, I immediately noticed the bike did turn slower. One thing you have to be careful of is the tire rubbing on the front of the swing arm near the pivot point. Race tire profiles are really tall compared to stock tires anyway, and by putting it on a skinny rim will make it even taller. Obviously you could adjust the chain length to compensate, but the fit is still tight. I haven't ridden a 195 so my imput on that would be worthless.

It comes down to personal preference. If you do run the 190 or 195's 55 or 65 make sure you adjust your geometry accordingly. IE tall tire in the front, drop the triples. Tall tire in the rear , lower the ride height adjuster. A good comparison would be to run your bike with the current tires, switch to the 190 or 195 and make the proper geometry adjustments back to back. Your compression and rebound may need to change, but that's a whole other thread.

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What I want to know= will the enhanced contact patch really help if it is on the 5.5 rim?

= what are some other issues that may arise because of this change.

 

 

Yes the tire will still "set" when mounted on the narrow (5.5") wheel. you will get the same type of contact patch as the 6.0", the difference is negligible in the tire. You would be more likely to feel the difference in the two wheels and what that width does to the handling than a difference in the tire when mounted on the two wheels.

 

The NT tires are a point and shoot tires, pick it up and nail the throttle type riding. Not fitting to my style of riding, it took a little while to get used to how much of a "set" they take in the middle of a turn. it's like the bike wants to stand up when you get on the gas, I think is from the tire folding to rim in the contact patch and not staying round like the G tech tire did.

 

I have never been very concerned about the size and profile of the tires or the wheel width though there are slight differences in what they do to the bike. Knowing what they are is a long way from being able to gain some advantage from them. Just because the fastest guys use NTs doesn't mean it is the best choice for everyone. If you can come to grips with how much they move to take a set they work very well on the 600s.

 

Will

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I appreciate everyone's input. I have decided to give it a try in September when I can get on the track again. I also spoke with Jim Cox who is a Dunlop vendor and he recommended the change and he said that I would like the outcome. He did recommend that I gear down a little to compensate for the change in tires because the dunlops are very heavy tires compared to other tires.

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I am not experienced with this particular tire change, but maybe you misunderstood what Jim Cox meant...

 

You may need to add a tooth to your rear sprocket to compensate for increased rotating mass of the larger tire, but, if Dunlop tires were SO much heavier than other tires that it required racers to add teeth to the rear sprocket to compensate for using a Dunlop, it would be a distinct disadvantage... and... nobody would use them.

 

Dontcha think?

 

Also, more likely, assuming the same aspect ratio (second number that expresses the height of the sidewall as a percentage of the width, 65 % of 195 mm in this case), the wider tire will be taller as well. Hence, you might need to add a tooth (or more) to your rear sprocket to compensate for the larger circumference of the rear tire.

 

A larger rear tire will cover more ground per revolution. Hence, your speed will be higher for a given RPM. It is effectively the same as making the rear sprocket smaller.

 

 

racer

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I have significantly edited my last post due to a brain fart regarding adding/losing teeth to the rear sprocket to compensate for a larger rear tire circumference.

 

My sincere apologies to anyone who was confused by the bad data I posted. Hopefully the new post makes more sense.

 

D'OH! My bad!

 

racer

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  • 3 weeks later...

I currently have the 211 GP's on a 5.5 rim on my track bike, they are the 200/55 and are a very, very tall tyre.

A mate runs them on his R1 and even on a 6'' rim, they need more muscle then the 209 ntec's.

To give you an idea, its currently harder to tip in then my gsxr1000, although that has been valved and

had a decent amount of set up and saddle time on and in all fairness, the track bikes probably only had 5 sessions.

 

I am currently playing with it a bit as the front wanted to tuck and didnt give me the confidence to pick up corner speed which probably would have made them a bit more stable.

 

I tried the slow in, fast out and maybe I did it on the wrong corner but the bike head shook at maybe 50% of the steering sweep (no damper- yet)!

 

I have set the forks flush with the top triple to increase trail.

I added a 3mm spacer to the shock which gave about 9mm ride height at the rear- the tyre is so tall it reduces swing arm angle... which is sort of counter intuitive but I made about a 6mm change in fork height.

 

Currently, it would seem that the tyre has a massive amount of grip but the negatives associated with it at my pace make it apparent they are more of a pain then what its worth

 

Unfortunatly, I dont have a base line as I got it like that so all I can really do is use my limited experience which will generally lead me in the right direction

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Well I tried it last weekend at Arroyo Seco Raceway in New Mexico and at first they felt weird but after Roger (the track owner) helped me a bit with the suspension it was freakin awesome. The bike was very stable in corners and had lots of grip. The track is at 4000+ ft elevation so it was hard to tell if the bike felt lethargic due to tire weight. All in all I would recommend it and was very happy with the change to the larger tire. Oh and I would tell you guys the exact settings for my new setup but Roger said it is top secret. LOL! I will just tell you that we dropped the front end signifigantly and raised the rear end a tad.

 

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