What a Difference 2cm Makes

A while ago I wrote about A Wheely Interesting Dilemma which came about after I bought Katy some new tyres

I had a problem with scrubbing on full lock which i knew would be an MOT failure

I had thought that it was an issue with the new tyres being wider, and so I looked into wheel spacers as I talked about in that post

With all the wonderful feedback I had from LRO and LRS, and the learning I had about wheel offsets, and information that having scrubbing wheels was an MOT failure I decided that before I did anything else I needed to get the front and rear wheels swapped to see if the more negative offset wheels made much of a difference to the steering and especially to the scrubbing, because the MOT was coming due

I have, and it does. 

The difference in offset according to my measurement of the front of the plate that is attached to the hub when measured to the plane of the front end of the rims is 2cm. I am presuming that this is reflected in the offset either fully or in part because I don't have wheels without tyres so can't make all of the measurements necessary to be definitive about this. Either the hubs are 2cm more offset or they are wider and some of this reflects in the offset.  At some time I'll have wheels without tyres and I'll try and work it out, but for now I'll just accept it

What is even better is that I've been offered some more of the wider wheels so I can get her to having all the same wheels and I don't need to worry about it in the future

Wheel options ?

As I wrote in A Wheely interesting dilemma I was looking into what I can do about Katy's mismatched wheels which is a situation I'm not really happy with

This posting is about some of the research and information I've gathered whilst looking into this and some links to some sources of information to explain the concepts I've learned

The Problem

Wider wheels scrub on the radius arm (or other aspects of the inside of the wheel arches) or you want to just make the tyres look bigger and have potentially more stability by having a wider axle width on the road or you need more turning circle (all of these would be nice on Katy)

Spacers

What they are for, is to move the wheel further out from the hub. This has the positive of making the wheel look bigger, and it gives some additional space when turning the wheel which will give increased turning circle and stop the tyre rubbing on the radus arm (or anywhere else) which is why I was looking into them

The trouble is that they are heavy lumps of metal and the effort of moving them around causes more strain on the suspension and transmission, and can increase bump steer which is a steering effect you get when you change the suspension geometry of any car, and it's bad because Excessive bump steer increases tire wear and makes the vehicle more difficult to handle on rough roads which is where Land Rovers are meant to go.

I've also heard (especially from the really helpful people on Land Rover Scene ) about all of the problems you can have if they are not absolutely tightened and come loose behind the wheel when you are driving, which ase led to wobbling wheels and even wheels coming off on the motorway, and also that many insurance companies don't like them

The guys on Land Rover Owner explained more

"Quality is very important as you are putting load on them from the hub to the spacer then from the spacer to the wheel from acceleration, braking, bumps, cornering and centripetal [see comments] forces from the spinning of the wheels and spacers themselves.Spacers should not effect wheel balancing as most spacers are turned on a lathe. Spacers can cause slightly higher wear rates in brakes and wheel bearings due to the extra forces they have to deal with under breaking and turning due to larger moving mass that comprises of the wheel, tyre and spacer combination when compared to wheel and tyre only"

OK that's enough for me to explore the other option which is why I then asked the same experts about wheel options and got a lot of comments about wheel offset which was something else I had never learned about so here is what I now understand about those concepts

Offset wheels

Wheel offset is the difference between the mounting plate that connects to the hub and the centre of the wheel. Fitting wheels with different offsets will move the tyre out like a spacer or inwards. Moving it outwards requires you to put on a tyre with a smaller (or negative) offset whereas making the tyre move inwards requires an increase (more positive offset)

To help you get your head around the concept this diagram may help

So to get more room for tyres to prevent scrubbing on the body or suspension which is the problem I've had I need to get wheels that have a more negative offset.

If I wanted to fit bigger wheels but had a problem with them sticking out of the wheel arches I would need to fit wheels with a more positive offset because that brings the wheels further back into the arches

It's been suggested that all four should be the same as the ones I have on the rear and I will certainly investigate getting some more like that

I've still got more thinking about this to do, and I need to get under Katy and on top to check out all the wheels I have and work out wat ofset they have, and see what I should have and make decisions

A Wheely interesting dilemma

Some time ago I bought Katy some new tyres which were a little wider than the ones she came with

Since then to be honest is is possible to get the tyres rubbing when applying full lock and i believe that this is an MOT failure so I've been looking into the options to resolve it

I considered just adjusting the stops, but to be hones she probably needs every little bit of turning circle she can get

I considered wheel spacers, but the advice from all the people on-line at LRO and LRS on this topic really seems to have come down on the this isn't a good idea. Steve Walford my master mechanic friend agrees with this stance

So it's either back to plan A or have a closer look at the wheels. I've known for a long time they were different. On the front (shown below) the space from the wheel rim top the bolted centre is 6cm

On the back (shown below) it's a little over 8cm.

This makes me think about swapping them around or getting 2 more wheels like the rear wheels to put on the front.

I think I need more advice before I decide so I'm going to call on all those on-line friends yet again (and a few more!)