Calibre Bossnut Rear Tyre and size

skippy_77

I did a post months ago, and was told I could fit a 2.35 tyre on my Calibre Bossnut V2.
However looking at it and getting a ruler between the legs/supports i could get at least 2.8"
Just wanted to know any riders with the Bossnut and se what width they've fitted and what tyres they've gone for.
Is there a rule of thumb for tyre size on the rear i.,e. take 5mm off either size in case the wheel buckles or flattens to stop the tyre rubbing on the supports.

robertpb

Why would you want anything bigger than a 2.5 tyre on a full susser, besides what's written on the sidewalls is not what you get. The frame you have is designed for a max tyre of 2.35, the forks are a different kettle of fish, also remember as the tyre widens the depth increases.

JBA

What size tyre is on the front, skippy_77?
Ideally you want the rear tyre to be narrower than the front one.

whyamihere

The problem with the Bossnut is the clearance to the seat tube. Take all the air out of the shock and compress it all the way. The rear wheel on my v1 was close to touching the seat tube with a 2.25 Nobby Nic doing that test.

skippy_77

I don't think I can get away with anything larger than 2.6"

I've been looking at the WTB Trail Boss or WTB Vigilante. Properly in 2.6 or 2.5.

Just wanted to know what people have put in their rear tyres on their Bossnuts.

I've got a 2.3" on the front.

robertpb

The WTB vigilante is not a tyre you would normally put on the back wheel, faster and narrower tyres for the back, wider and grippier tyres on the front.

A 2.4 is plenty big enough on the rear, on your bike in some brands that may be too big, Schwalbe tyres come up on the large side, my Magic Mary 2.35 at 62mm is as big as some 2.6 tyres, so as previous posts care must be taken.

JBA

You have your tyre configuration the wrong way round. Put a 2.5 on the front and a 2.25 - 2.35 on the rear.

steve_sordy

There are several reasons why I would not put a tyre that size on the rear of your bike.

#1 It is important to get the grip balanced front to rear. Ideally you need more grip on the front so that when cornering hard the rear lets go first.
#2 Having a faster rolling tyre on the rear helps to reduce drag on those long climbs that happen from time to time.
#3 What is the internal width of the rim on the rear wheel? For a 2.8" (71mm) tyre the internal rim width needs to be at least 30mm so that they tyre has a decent shape and doesn't look like a balloon. The shape has to be good otherwise the tread is not properly presented to the trail and you won't get the grip you are expecting. Also, the tyre beads will not be properly secured to the rim, which risks the tyre coming off the rim if you are pushing hard. See the link to the Schwalbe tyre knowledge sight, click on "which tyre fits which rim", look down the left to 70 and across to your rim width to see if it fits.
https://www.schwalbe.com/en/reifenmasse.html
#4 You need room between the tyre and the frame. The frame flexes, the wheel flexes, the tyre carries mud and grit. The last thing you want is for the tyre and the frame to contact each other. Don't forget how close the wheel can come to the seat tube when the shock fully compresses, let the air out of the shock to check.

If you want to use a tyre that size on your bike, you would be far better fitting it to the front wheel, provided if will fit under the fork brace and reasons #3 and #4 above.

Ask yourself why you need more grip on the back? Is your rear wheel spinning out when climbing out of holes or up steep hills? If so, you can increase grip by changing the tyre for one of the same size but with a better tread pattern or one with a softer compound. But be careful about #1 and #2 above.

skippy_77

I've always thought putting the wider tyre on the rear was advisable as there's more weight there.

I weight 95kg.

I already have a 2.2 tyre on the rear, I'm finding this does not give me traction in the mud what so ever.

I have 2.3 WTB Vigilantes on the front and 2.2 WTB Bee Line on the rear.

I like the Bee Line and using it on the dry trails but it's terrible when going over leaves and mud. It just digs into the mud rather than cuts through it.

I won't get anything wider than a 2.5. I understand that the width stated can sometime be narrower depending on the stated recommended psi. So a 2.5 may be 2.5 @ 60psi but would measure around 2.3 @ 35 psi.

In the mud I pump it between 30-35 and 40 in the dry.

robertpb

You can't put 60psi in a 2.5 tyre it would be well over it's limit. Tyre sizes are normally measured at 25psi.

The Bee Line is a tyre for conditions we don't have at the moment, plus you're running too much air for mud, 27-29psi is probably enough for your weight, 2-3psi less in the front.

JBA

The Bee Line is designed for XC and hard-packed, dry trails. Useless in mud and slippery conditions.
You need to change to a more suitable tyre for the winter.
You could put the Vigilante on the rear and get a new WTB Convict 2.5 for the front, or run Vigilantes front and rear.

cooldad

The size of the tyre won't change with pressure, fat tyres do not work better in mud, and your tyre pressures look way too high.

steve_sordy

Drop your pressures and you will have a much better ride, more grip and less jolting.

This is a link to a great article con setting your ideal tyre pressure. Its from Pink bike's Tech Tuesday sessions. Read the words and watch the video. Transforming!

https://www.pinkbike.com/news/Tech-Tues ... -2011.html

I'm 14.5 stone (90kg) riding weight and I ride with 27.5 x 2.3" tyres 22psi F and 27.5 x 2.2" 24psi R. I have a Maxxis High Roller II 3C on the front and a Conti Trail King with bcc on the rear. The rear tyre was a Maxxis Crossmark II 2.25" on the rear, but although it was great in the summer, it had little grip in slippy conditions, even a little mud would have it spinning out.

skippy_77

Thanks gents, I'll go for Vigilantes front and rear. I'll drop my PSI, and know this will make an improvement.

I'm not going tubeless just yt, are these tough tyres less likely to get punctures?

skippy_77

I bought 2.5" WTB Convicts, they're great. Used them in the mud loads, seem to dig in and grip very well and lose the mud as i'm riding. 2.6" might fit, but glad i went with the 2.5"..
Set the PSI as recommended and the ride feels better.
Bought the convicts from CRC, a pain to put on tubeless ready rims and bought some puncture resistant DR Sludge rim tape as I don't want to be having to try to get these tyres off on a trek.