Bigger tyres

[twin wheel camper]

Any brain surgeons able to work out how much of a difference fitting 235/85/16 tyres in place of 185/80/15 will have on a my 100 ps twin wheel high cube transit fitted with a 5.14 diff, not worried about clearance at the minute just how much it will alter the gearing. I also have a 4.63 diff here and was thinking which would be better bigger tyres or getting the 4.63 diff fitted the 4.63 diff is of a 6 stud single wheel transit so can't just fit the axel to my twin wheeler.
235/85/16 with need 16" wheels or course but will get a set of mk6 tipper wheels and redrilled to suit mk5 hubs,
Maybe 235/85/16 are going to far and might up the gearing to much that's why I'm looking to see if anybody can give me the figures in % of the difference thanks

[MinorMatt]

http://www.autopartuk.com/tyre-calculator/

[twin wheel camper]

So it will reduce revs from 780 revs per mile to 655 revs per mile, anybody translate that into English
The circumference is 18.7 % bigger and 4" bigger in total height.
My brain doesn't like things like this so this is of little help to me but there's others on here that can translate it I'm sure

[joinerman]

www.kouki.co.uk/utilities/visual-tyre-size-calculator

[MinorMatt]

16% reduction in revs

[twin wheel camper]

Thanks Matt just for reference how much will standard tyres and the 4.63 diff reduce revs

[MinorMatt]

4.63 reduces revs by approx 10%

[twin wheel camper]

Thanks Matt for that, 16% is probably going to far with it being a camper and best part of 3.5T all the time, 10% would probably be closer to were it should be.
It's a 100ps turbo with plenty of power but without spending a fortune buying wheels and tyres to the find out if it is still ok to drive its just to risky,
I was looking also at 235/75/15 tyres and that is probably a happy medium but I'll think about it and then decide.

[MinorMatt]

My LWB high top is a 100PS which still has the EPIC.

It has a 4.63 with standard 225/70/15 tyres.

It will happily pull up hill/down dale fully laden.

I also run up to (and sometimes a touch beyond tbh) max train weight (5300kg) with a twin axle trailer behind. Its not ideal for that but stills pulls happily on the flat and has never felt like I am holding people up

[twin wheel camper]

Yea a good 100ps turbo di can pull no doubt about it.
Mines still on the epic as well but not sure wether to ditch it and fit a Bosch 145, i have a pump sitting here and all the bits needed to change it but the epic when running ok is a pleasure to drive.