Will 205/60-13 fit?
The general answer is that the section width is too wide to fit under the wheel arches of either the earlier S1-S3 or the S4-Sprint bodies, even if you have relieved the inside of the wheel arches and flattened the spring collars.
However:
If you have small diameter rear springs and wheels that move the tires in toward the center of the body, they might fit. I know 185s are a struggle, even on a S4. The other thing to consider is the front wheel lock. You just can’t crank the steering wheel as much as the tires interfer with the arb.
On a quantitive basis:
155-13 is 912 rev/mile, 22.8 in diameter.
165-13 is 887 rev/mile, 23.4".
175/70-13 is 917, 22.6".
185/70-13 is 893, 23.2".
185/60-13 is 956, 21.7".
205/60-13 is 916, 22.7"
225/45-13 is 990, 21.0".
185/60-14 (Spyder) is 915, 22.7".
185/55-15 is 904, 23.0".
In speed terms, if you have 6500 rpm and 3.77 this gives
155-13 113
165-13 117
175/70-13 113
185/70-13 116
185/60-13 108
205/60-13 113
225/45-13 104
185/60-14 113
185/55-15 114
If you are relatively sensitive, you can tell the difference between tires that differ by 2mph or even less. A good percentage of the population is not that sensitive, and will happily motor about with even a 10 mph difference.
So your 205/60-13 is practically the same diameter as the standard 155-13, although almost 2 inches wider. However, the wider profile will be more sensitive to camber changes while cornering and braking. So you will have to adjust initial camber settings (if you can) and use different roll bar thicknesses. There is a substantial amount of opinion on this site that the Elan does not handle as well with these wider tires, and you get the best handling with the old 80 series tires. You can be sceptical about this, or accept their arguments as you see fit.
However, the Elan with original tires was a .7g cornering machine. If you go with sticky modern tires, whether Michelin XAS FF 80 series, or a more modern 60 series tire, you can be getting 1g, more or less. This has implications through the car. Bearings, bushings, dampers, roll bars (and rear roll bars) are all impacted, as is the engine sump. The rear suspension suffers the most, since a strut suspension does not have as favorable geometry as a wishbone suspension. To alleviate this, you can go with the Spyder chassis, their wishbone rear suspension, adjustable upper front and lower rear wishbones, and test equipment to properly set up your car. It is not simple, that is why so many of us stay with relatively standard tires.
You ask a simple question, do you get a simple answer?
David
1968 36/7988