Definitive tyre advice required

Joined
Feb 22, 2016
Posts
4,937
Likes collected
19,872
Location
York
Funster No
41,744
MH
Bailey 620 Approach
Exp
Since 2015
Van: 2012 Bailey Approach 620 SE.
Current tyre size: 215/70/15 load index 109.

As part of increasing our rear axle limit from 2000kg to 2400kg we’re having rear air suspension fitted. Will have the van upgraded to 3850kg from 3500kg.

We’re required to increase the load index of the rear tyres to 112. Only tyres with the requisite 112 load index are 225/70/15. Lenny HB and others have pointed out that this size tyre will fit 15” wheels. All good so far but I’d still like to know whether we have to replace all tyres to 225 from 215 (including the spare). We have had warnings that the the larger tyre on the front wheels may foul the suspension when turning, the spare tyre carrier will need to be modified to fit the larger tyre and that so far as the rear wheels are concerned, we may have to trim some of the plastic moulding on the rear arches to accommodate the physically larger 225 tyre.

I’m going out to the van tomorrow to have a look but I recall that there ‘s masses of space around the front wheels and find it difficult to accept that there will be any fouling with the suspension when turning, with the larger 225 tyre. And although less clear, it also seems unlikely that the 10mm increase in tyre size will foul the rear wheel arch. But these are just my opinions.

What I need to get clear in my mind is whether increasing the tyre size will affect the MOT and if there is any difference if we opt to only fit the larger tyres on the rear as the necessity for the uprating requirement and keep the front tyres as they are with a lower load index.

Obviously, we will have the same tyres on the same axle. But is it a MOT requirement to have the same tyres on both axles?

This then brings me onto the the spare. If it’s the case that only the smaller 215 tyre with the 109 load index will fit the tyre carrier, then if we carry this size tyre it could not be used on the rear axle. And if we opted for the larger tyre as the spare then if couldn’t be used on the front axle.

In a bit of a quandary. Want to do what’s safe and legal but there’s a large difference between buying five tyres rather than 2. And that’s before any issues of the larger tyre possibly fouling the suspension or rear wheel arches, both of which sound illegal to me.

Sorry for the length of this post. And again, I want the legal position rather than opinions or guesses. I don’t mean this disparagingly, just that I’m fussing and time before we get the suspension fitted is fast approaching and SV tech will be doing the upgrading when all’s done.

Thanks in anticipation. I know I’m asking a lot!
 
The Bailey must have very tight wheel arches if 10mm extra width ( that is 5mm either side of the rim width) is risk of fouling.

I had 225 , 70, 15 fitted to my Adria after upgrading to 3850 with absolutely nothing to worry about. (Fiat base vehicle).
 
Would suggest a reputable tyre fitting garage should be able to answer this for you.
 
Why not put a very cheap, second hand or part worn 225/70 15 tyre on your spare and try it out, though I very much doubt there is anything to be concerned about. Our 2014 Fiat based Hymer was fine for the 7/8 years we had them on.
 
Last edited:
You will only find out if the 7mm increase in radius is an issue with the wheelarch on full suspension compression which is virtually impossible to check but it's such a small increase I wouldn't worry about it. If you have more than 5mm clearance to the tyre from any suspension when just sat sitting and turning lock to lock then the increased width won't be an issue.
 
I have just gone from 215 to 225 and there is no fouling. 2k miles to Bettyhill and back from Cornwall so plenty of different conditions.
 
Why not put a very cheap, second hand or part worn 225/70 15 tyre on your spare and try it out, though I very much doubt there is anything to be concerned about. Our 2014 Fiat based Hymer was fine for the 7/8 years we had them on.
A good tyre fitter will ALREADY have one of these sat for this purpose.

(ours keeps tyres of all sizes for fitting purposes in stock, not new, tread is shot on them).
 
Change all the tyres to 225 section. If you only change the rear, there will be a (slight) difference in rolling diameter as already said. This difference might interfere with ABS and traction control systems.
 
You don't say what can your moho is based on.
My PVC is Fiat based.
Changed my original wheels/tyres to 215/70/16.
Reason for 215 instead of 225 is that it put my Speedo right!
This gets you bigger range of tyres with the load rating you need, and an added bonus of better road clearance.
 

Join us or log in to post a reply.

To join in you must be a member of MotorhomeFun

Join MotorhomeFun

Join us, it quick and easy!

Log in

Already a member? Log in here.

Forum posts reflect the views of individual users and not MotorhomeFun.
MotorhomeFun does not endorse or verify user-generated content.

Back
Top