I’m doing a bit of speculating for a future project.
I have a vision of a Disco 1 V8, completely standard on the outside, including standard bumpers, but with wheel arch extensions if needed.
So what size alloys and AT tires could I fit, not going any higher than a 2 inch lift. I like the idea of fitting alloys bigger than 16inch.
Depends what you want to do really.
If you want to retain stock bodywork and not go off road, then you might squeeze a 7.00 or 7.50 x 16 or a 235/85R16 on. But most likely these will impact the rear of the rear arch under suspension compression, so unless you bend the bodywork or perform the 'Camel cut', it won't be able to go off road. Which will likely limit you to something nearer to a 245/75R16.
As for lifting to fit bigger tyres. A suspension lift doesn't really work IMO. Sure when the vehicle is just sat on the drive or on level ground you'll have more room for bigger tyres. But under suspension compression, all your suspension lift will be lost. And the tyres will still impact the bodywork. Unless you are running silly HD springs which don't compress and ruin the ride that is, but I wouldn't advise this. You could also fit extended bump stops, but this generally just reduces wheel up travel and reduces off road capability.
A body lift in theory would give more room for tyres, but not usually off the shelf kits for a Disco, also a bugger to fit, generally make the vehicle look horrendously ugly (like it has been in an accident and badly fixed). And you'll end up needing to look at extending things like the gear linkages, steering column, rad hoses and loads of other things. So can be pricey overall.
If you are happy to cut/trim the arches you'll be able to fit much bigger tyres and not even need to lift the vehicle. Remember you are already running the same ride height/spring length as a stock Defender. Which means compared to many other 4x4's you are already about 2" better off anyway.
Also as tyres get bigger you'll find they tend to get wider too. This means under compression they won't sit inside the body work, but directly impact the edge/lip of the wheel arch. So trimming the arch and fitting flares will allow taller and wider tyres to be fitted.
As for alloys, not really my thing. Also not sure what is available to fit the stock Land Rover PCD/hub. Suspect you might find an 18" rim, but tyre choice is often less than with 15 or 16" rims. As a rule the bigger alloys will reduce ride quality as you have less sidewall on the tyre, unless you are going very big.
To retain any sort of steering lock you'll want to look at deeper offset rims and/or wheel spacers more than likely.
As for overall dimensions. I used to run Simex 33.11.50R15's on my 3 door 200Tdi Disco. These where on 15x10 steel rims and spacers to increase the offset (with the spacers the offset was equivalent of ET-17.3). The Simex tyres measured almost 34" tall and I was on stock suspension. Just trimmed arches. I suspect a 5 door might be a bit harder as you can't trim the rear arch as much. But there are people running 35" tyres out there on Disco's. But more hacking and a mild lift might be needed.
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