Tyre sizes and how they differ

A few weeks ago I picked up some cheap Maltesta tyres in a 215/80 mounted on a 7" rim with 100mm backspacing. I got them on today after fitting a 2" lift and they are huge, lots of clearance problems.









On my old Jimny I had the same size tyre, 215/80 made by Colway, mounted on 5.5" SJ rims with 95mm backspacing and no suspension lift:



Both sets of tyres are remoulds. I'm not fussed as the Maltestas will go on another vehicle and the rims are as good as new so I'll reuse them with a new set of tyres. The original 5-spoke alloys are destined for my SJ413 pickup. I just thought that the pics illustrate nicely the problem of simply quoting tyre sizes.

For some off-road tyres you need to ask what the "Rolling Radius" is when purchasing.

I had a long discussion with a dealer who helpfully quoted both the sizing printed on the tyre and also the rolling radius when quoting for tyres. He pointed out that a lot of tyre dealers do not do this and it leads to a lot of confusion in 4x4 markets where the "same" tyres do not fit.

Get the grinder out and start cutting :laugh:

I think its mostly the width of the rims that's causing the issues, according to the tape measure the height is about right and moving the outside edge of the tyre in would give a lot more clearance. The Maltestas are going on SJ rims so I will try them again when they've been remounted.

Yes, the wider rims with only a little more backspacing will move the tyre out towards the edge of the arch. You need 115mm backspacing to put the tyre in the same position as on the narrower rims.

Well I've taken a tape measure to the tyres, the stock 205s measure around 200mm wide. The 215s measure around 235mm wide! they are clearly marked 215 but appear to be closer to a 235/75 in size, combined with the 7" rims they stick out a lot further than the old 215 Colways did.

I have found that retreads seem to come up bigger especially the tractor looking ones. It is very helpful if they can tell you the overall height of the tyre. Those tyres look nice and business like!!

I did check the height when I first got them and it checked out about right at around 28.5". I didn't check the width though as I've not had a problem with that in the past.

It almost sounds like they are selling 235s as 215s. I wonder how their 235s measure up?

Busta wrote: It almost sounds like they are selling 235s as 215s. I wonder how their 235s measure up?

That's what it seems like, they do have 215/80 moulded in the sidewall.

I remember a test of 205/40/17s in an old Max Power magazine and they found actual widths and diameters on new well known make non remould tyres varied by quite a bit, some were as narrow as 195mm and some as wide as 210mm

The rim width will make some difference, usually the tyre width is specified for a given rim width. I measured the 205s on the Jimny rim and they come in at around 200mm. The problem with remoulds is these dimensions are rarely specified and they are exempt from many regulations.