Rear tyre size and rim locks?
 

I need new tyres for my XTZ660, and I'm planning to get some TKC80's. The current rear tyre size is 130/80R17, but the Continental website tells me I should have 120/90S17. I don't know which measurement the numbers or letters refer to and I cannot find any info in my manual or on the web that tells me which is the correct size to fit. Will it make a big difference to the bike performance, if so does anybody know which size I should pick?

I wanted to go tubeless, but I understand that I'd have to change the rims aswell so I'm going to get some heavy duty inner tubes and rimlocks - are rimlocks a good idea and are they easy to fit to the existing rims?

Thanks to all.

Butch

Rim locks tend to be fitted to bikes that run lower pressures (typically 15psi or less) such as dirt bikes in competition - the aim being to stop the tyre moving/spinning on the rim under power, and potentially ripping the valve out of the tube.

Most off-road orientated rims will hold a tyre just fine at 18-20 or more psi, it's only under extreme acceleration at lower pressures that a tyre might slip.

For general travel on or off-road, you are probably going to be running similar pressures (or higher) unless you are aring the tyres down for soft sand for example.

I had rim locks in both my Honda XR400 and 650Rs, but after fitting mousses for a rally earlier this year, when it came to refitting tyres and tubes, I left the rim locks out for my trip around Europe and Morocco, and it hasn't made the slightest bit of difference.

If you do decide you need them, one thing you should consider is that rim locks do alter the balance of the wheel, which is why some people fit two (opposite each other). It is a case of simply drilling a hole through the centre line of the rim for the bolt to go though. They do make things a little more tricky when refitting a tyre, but not significantly.

Personally for overland/adventure riding, I'd not bother unless you'll be doing a lot of soft sand work - just fit some decent heavy duty tubes and the tyres you suggest are a good choice for on/off road riding - if your rim already holds a 130 width rear, then the 130 TKC would be fine. (for your info with a 130/80R17 the 130 refers to the width in mm, the 80 is the % ratio of sidewall depth of the tyre compared to the width, the R is speed rating (or sometimes can also indicate Radial belts) and the 17 is the wheel rim diameter in inches).

xxx

Great Advice.
 

Excellent stuff, that's pretty much solved my dilemma. I think I'll bin the rimlock idea and go for the larger tyre.

Thanks JMO :thumbup1:

The other information is correct, :thumbup1: but the R is NOT the speed rating, :oops2: it IS indicating a Radial tyre constructon. The R in the middle of the service description refers to it's construction type.

The load / speed index appears elsewhere on the tyre.

Continental know which tyre that they make works best with this bike, so follow their advice on the size for the best performance. The original equipment tyre must not have been a Continental, and they found that that size worked best for the tyre that they make.

I agree R in that position usually refers to Radial construction, it's just the other size he listed had an S in it - not sure what that refers to unless it is a (lowish) speed rating? Unless it means crosS ply perhaps?

xxx

Thank you both for your information so far.

Angus, do you also think that rim locks are not such a good idea?

I've no experience with rim locks at all, so can't comment.

If I was going to run such low pressures that I might need them, I'd look into them, but I don't.

My riding is UK - green laning in the peak district and so on, so I run knobbly tyres (Michelin T63's) at road pressures. If I was riding constantly off road, I'd drop the pressures. If I was riding constantly in very soft conditions (sand or mud), I'd lower the pressure further, but it's allways a compromise, tbh.

Here's a good explanation of tyre sidewall markings: Dustcap.co.uk - Tyre Guide

Great, thanks.