17" wheels, tyre size
 

I have an Amazon 122s sedan fitted with -30mm sport springs and would like to fit 17” Torq Thrust wheels. Could someone offer advise on what size tyres to use please?

My research so far indicates 205x50x17 or 225x45x17 may be suitable?

Any help/comments particularly from owners with 17” Torq Thrust wheels and a lowered car would be greatly appreciate.

The exact spec of the wheels I’m looking at is:
American Racing AR105M Torq Thrust M 7.5x17 5x114.3 ET 45

Many thanks

This site is good to compare new to old it also shows you how much you have changed scrub angle
https://www.wheel-size.com/calc/

ET45 is not gonna work well. I have been asking similar questions and have gotten various answers. 17x7 or 8 ET0 or somewhere around there is what will work on these cars. Some people have done various modifications. I have seen 17x7 or 8 ET20 work as well and maybe with spacers. Sorry I dont have a definitive answer...if you get one, I would love to know as well, because I plan on using 17 wheels on my wagon, but I can't get a straight answer as to what width and what offset works to fit inside the wheel without rubbing or modifications.

Use the link I posted earlier it will tell you how much the tyre will move in towards inner wing and out to wheel arch
On the screenshot the widest it recommends is 195 but offers a 205 as close offset is 25
You can play around with width and offset and it gives you the dimensions to check on the car
Pay attention to the scrub radius on the front the more you go away from 0 the heavier the steering will be, I went from 165 to 195 and could hardly tell the difference because I kept scrub radius as close to zero as possible, if I was to change wheels I would keep the fronts as they are and go an inch wider on the rear for no other reason than looks

Hi, many thanks for this, I agree, further research shows ET45 is not so good.
Now looking at 17x7 wheels with ET0 with a 215/50 tyre
Quite interestig:
https://www.youtube.com/watch?v=K0vJ..._0ICD&index=59

That would put the tyre 45mm further out than the original tyre, will it fit?
Calc suggested 205 45 with a 7 inch rim et 25
That would put the tyre 25 mm closer to inner wing and 15mm further out compared to standard wheel and zero scrub radius
If you want 215 x 50 you need ET20 that would give you 25 mm closer to inner wing and 25mm further out to arch this is also zero scrub

Having a small scrub radius is beneficial as it allows the wheel to react less to braking inputs due to the smaller moment arm and increases steering stability under braking conditions.
I found a good drawing one day of the Front Suspension of Ferrari F40 and it had a considerable amount of Scrub radius. The F40 has been commented on many times on how good the steering and the feel is by many top drivers.
Also if you read books on Suspension Design by people like Allan Staniforth he hardly mentions Scrub radius as its not that important.
If there is no scrub radius you have very little feel through the wheel, certain Audi's and VWs had this and with the addition of Power Steering the steering feels dead.
So a few mm of Scrub radius is no problem, its more important to get the proper clearances so the tyres don't catch on anything.

17 x 7 wheels have been used but at this point I don't now what is the best ET. I would consider refitting the original springs and then see how the larger wheels fit. If you can get a single 17 x 7 with a suitable tyre, good condition not essential you can then see how it fits front and back. Original Mustang wheels will fit. 215-225/45? Front clearance will be the problem but the lock stops can be adjusted to help you a bit.

In the end I went for American Racing Torq Thrust 7x17 5x114.3 ET 0 wheels.
With Goodyear F1 205/50 tyres and there are no clearance issues at all.
The car is an absolute joy to drive now, I'm delighted :regular_smile:

ET of 10-15mm would be best usually