Are you planning on opening up the wheel wells? If you are talking 8" or 9" widths, I think that is a given.
I'm not opposed to it but I'd love to know what it will take stock with the right offsets I'm sure something could work out. And this is on a 76 Scorpion.
I'll be swapping to the Koni single way adjustable coilovers if that helps.
Another factor to consider is weight.
) Greater inertia due to weight is the culprit here. More load to manage by the shocks and springs as the tire bounces up after going over a road imperfection, keeping the tire in touch with the road is what is important.
Why the wider wheels/tires?
Largely for looks, partially to find tires that fit considerably easier. Obviously I'd be looking for the correct offset and so on as to not cause more wear on suspension parts, I'd also only considering getting "real" wheels, meaning quality forged 3pc design. I will be K24A swapping it as well and 250+ hp on 5.5in wheels doesn't sound ideal to me. As I said before I'm rebuilding the suspension and using the Koni adjustable coilovers from midwest bayless likely with use of their camber plates as well.
Another factor to consider is weight.
Larger rims weigh more than the OE 13” rims, heavier rims affect acceleration, braking, handling, ride and by extension economy (which none of us care about
There is a limit to the value of adding tread width on a light car, you get to a point of diminishing returns quickly. The biggest value from a performance perspective of going to a 15” tire/rim combo is the reduced reaction time/stiffness of the shorter sidewall, at least on track or autocross. Modern cars need more tread width as they are dealing with much more weight, a GTI in 1983 was just over 2100lbs, today they are over well over 3100lbs.
I would use a tire/rim calculator to map out what is possible without major changes but as Ulix points out, diameter is going to be the limiting factor. Old cars had smaller wheel openings and wheel houses with an intended relationship of the wheel/tire assembly to the strut assembly. With coil overs you will gain vertical space potentially but you will run out of wheel opening. With a larger overall diameter you will change the final drive of the car making it in effect ‘taller’ which will negatively affect acceleration even more (larger circumference, more weight to turn equals poorer acceleration).
I have included a PDF from one of the many calculators out there which gives a very good summation of wheel/tire setups.
It absolutley always does. If you raise the OD, you raise the gearing and you DECREASE brake power and unless you lower the car back again , you raise CoG whitch reduces cornering power and increases load transfer forward under braking. If you lower to compensate, you still have taller gearing and reduced brake power, plus now you have reduced suspension travel and suspension geometry operating away from the design point. No worries, now we fit bigger brakes and do a whole bunch of serious changes to get suspension geometric control back - oh and we probably need to some work on steering along the way.
Welcome to the forum
Off topic is what we do best!Becuz grippy tire compound accomplishes same function besides appearance of wider tires. Race tires also have the appearance of speed.
OD change would be small difference. Its not putting 36 inch tires on a lifted truck which people do everyday without swapping gearing. With the K swap won't be the Lancia gearing. With the coilovers can set to desirable ride height allowing suspension travel.It absolutley always does. If you raise the OD, you raise the gearing and you DECREASE brake power and unless you lower the car back again , you raise CoG whitch reduces cornering power and increases load transfer forward under braking. If you lower to compensate, you still have taller gearing and reduced brake power, plus now you have reduced suspension travel and suspension geometry operating away from the design point. No worries, now we fit bigger brakes and do a whole bunch of serious changes to get suspension geometric control back - oh and we probably need to some work on steering along the way.
In summary, unless you are talking doing all the downstream changes, don't change the OD.. If we are talking race - all bets off cos you need to change everything anyway
And... wide tyres come with increased sensitivity to dynamic camber change and the contact patch aspect ratio also makes them more skittish in response to road irregularities and more prone to aquaplanning and and and. But hey, have fun!
