Tyres (again)

[Andy W]

A similar question - a different size wheel.

I have 5.5 inch standard wheels on my '68, I want to put on wider tyres than the current 165 SR's (as it rains a lot in England and I need as much rubber on the road as possible!) but I don't want to alter the rolling radius.

What profile will do this for a 185 and 195 tyre?

Thanks

Andy

[Rick Becker]

Andy:

A 185/70-15 will give you virtually the same outside diameter as a 165/78-15. Since a 5.5 inch wheel is 25mm wider than a 4.5 inch, the extra 20mm width of a 185 should be OK, but I'd ask the tire dealer if a 195 with its extra 30mm width will work with a 5.5 inch wheel. (I use a 6 inch Fuchs wheel, 32mm wider than a 4.5 inch wheel). Regarding a 195, the combination of 195/65-15 will give virtually the spec original outside diameter; however, I cannot predict what the fender clearance will be.
On my '68 with stock fenders, I used a 195/60-15, which has about a 2% smaller outside diameter. I felt more comfortable with the extra fender clearance.
One other thing to consider, is how well will a wider tire allow water to pass under it? I'd suggest you ask what is the best rain tire for your car.

Cheers,
Rick B

[Rick Becker]

Oops! Pardon my math, a 6" wheel would be 37mm wider than a 4.5" wheel. We still haven't really converted to metric yet in the States.

Rick B.

[Rick Becker]

Andy:

Another consideration: the wheel offset. Suggest you stop by the 912 Registry at:

http://pages.prodigy.net/beckers/912reg/index.html

Click on the Interactive page, once there click on the Technical hyperlink. We have some posting discussion the effects of wheel spacers and wheel offsets as it relates to tire clearances.

Cheers,
Rick B