What size tyres you running

[admin]

Trying to find a definative answer really. got a pair of rims from a XR400 which are 4.5" rear and 3.5" front so a pair of inner tubes to suit and a pair of BT090's needed.
But what size is the tried and tested without clearance issues

C'mon chaps could use some solid advice before i buy the wrong ones

[Jeram]

BT-090PRO Rear

TIRE SIZE...................REC. RIM (inch)...MEAS. RIM (inch).OD (mm)....TW (mm)
140/70R17M/C.............4.00..................3.50-4.50...........627...........146
150/60R17M/C.............4.50..................3.50-4.50...........620...........156
160/60R17M/C.............4.50..................4.00-5.00...........633...........166

Im running a BT003 140/70 of similar measurements to the 140/70 above which is 146mm wide.
in the swing arm there seems to be more than enough clearance on either side (10mm per side) and more than 10mm clearance to the chain to accomodate a 160 rear

let me know if you want me to measure my tire/swingarm/chain clearance :)

[admin]

good man thats what i needed to hear.
i have a pair of tyres i was going to stick in the RVF so they will do, just need some tubes, a rear sprocket, and am good to go i reckon

[Jeram]

great, well let me know if you need me to take any proper measurements.

but if youve got a wheel in your swingarm you can measure from the centerline of the wheel and work it out :)

[admin]

i dont, the bikes over in north wales, wheels here at mine in cheshire.
front is a 3.5" and rear is a 5" rim
so was going to get a pair of tubes and fit the tyres, then bring the bike back and offer it up to see if all was good.
dont know what to do about gearing i think that will be trail and error, i want it a bit geared for top end as it will only be used on the road and if it can sit smooth at 70 then thats perfect.
the different sized rear will throw the gearing out a bit i think

[Jeram]

try gearingcommander.com because Im such a champ, I loaded the CRM250 up onto that site :P

enter your rear tire size and sprockets and it will give you speed in all gears at various RPMs

[knackeredMk1]

viewtopic.php?f=20&t=5556

[Jeram]

actually correction, I now have a 150/60 BT003R on the rear in the 4.5 rim.

clearance on the swinarm is fine, but clearance to the chain is only a few mm.

Id say if you went to a 160/60 youd want to offset your sprockets 2mm or so to prevent chain rub.

but I know for a fact that people are running 160's in 5 inch rims, my mate has a supermoto CRM-AR with 5inch supermoto rims and a 160 tire.

[admin]

Cheers again
Won a talon caliper spacer on ebay, so just need to sort some fresh wheel bearings all round, a pair on inner tubes, and i can then get it all bolted together.
not sure what size gearing to go with though. close to standard speed would be great, maybe a bit more top end based. the gearing calc worked ok but it still was guesswork i reckon as it will be.

[knackeredMk1]

I've got a 150/60 on mine. I needed to run a non-o-ring chain and space out the sprockets at each end by 1.5mm to be sure of clearance.

Maybe I'm being too complicated but I've seen chainlube round the edge of the tyre and what it can do to the rider .

[admin]

how did you space the sprockets out ? washers behind the rear ? what about the front ?
correct about chain lube

[knackeredMk1]

I had a ring of stainless steel (as I remember ~1.5mm thick) made to cover all the bolts but washers would do. I also had several thicknesses of plates made to space out the front to get the two srockets perfectly aligned. BUT mine is a Mk1 so has a bolt on retainer for the front sprocket. Can't see a way to do this with other models . Maybe the tolerances are such that you can space out the rear without doing the front.

You can save 1.5-2.00 mm by using a non-oring chain, which you don't need anyway and also doesn't loose as much power.

[admin]

Hmm interesting. i need to go and get mine back asap to offer it all up and try it out.
just need to get some damn mirrors for it before i want to use it on the road now

[Jeram]

did you have to run a non-oring and offset for your 150? shite...

mine fits nicely in the stock mito wheel, oring chain, 5mm clearance to the chain edge

guess it purely depends on the wheels sprocket offset amount :S