Another wheel-size thread

[Loeblich]

Hi, I'm restoring my 72 Opel Manta, and I found out that the rims are very rusted. I was looking for rims with the same size as the originals (13 with 175/80 tires), but it seems that here (Venezuela) those are not very common sizes. I'm thinking in buying new rims, and need to know how "tall" can I make my Manta. I need it to be tall, because here the streets aren't in a very nice condition (holes and bumps everywhere).

I though of a 14 rim and a 175/70 tire. But does anyone knows for sure what's the "tallest" tire and rim I can use?

Thanks a lot

Javier Alvarez Löblich.

[BQS4]

There are some who have gone to 15" wheels on their Mantas, but, at 15" the wheels and tires get expensive real fast

[Loeblich]

Thanks for the reply.

I read some threads here about it. But it seems that most opel owners wanted to lower their Mantas. I'm trying to do the opposite. I'm note really interested in using the biggest rim as possible, but to get the "highest" setup. I think (but I'm not sure) that I could use a 14 rim with no problem, but I need to know what's the biggest (tallest) tire I can use with a 14 rim. Do you know that?

Thanks for the help!

[traytodd]

The stock tires on a Manta & GT are 165 78R13. I run 185 70R13 on stock rims on my GT. These tires have nearly the same diameter and circumference as the stock tires. As a result the speedometer is very close to being accurate. If I used 185 80R13 tires, I would have a larger diameter, hence higher clearance but the speedometer would read low. Also the acceleration would be reduced since the effective rear end ratio is changed. There are on-line tire calculators that will allow you to compute the different combinations of tire size and speedometer readings.

http://www.bigcustomwheels.com/info_specs.jsp

With respect to the numbers on the tires, the first number is the tire width in mm, the second number is the tire profile in %, and the third number is the wheel size in inches.

Example: 185 70 R13 Diameter = 590 mm Speedo reading 120 @120 km/hr
195 60 R14 Diameter = 590 mm Speedo reading 120 @120 km/hr
195 70 R14 Diameter = 630 mm Speedoreading 120 @128.2 km/hr

The last tire increases the ground clearance by 20 mm.
The other issues you need to be concerned about are fender clearance with the bigger and wider tires. For this you may need to change the offset of the wheels and/or add spacers under the springs or replace the springs with taller springs. This would also impact the shocks.

Terry

[2 Fast 4 U]

Originally Posted by Loeblich ......But it seems that most opel owners wanted to lower their Mantas. I'm trying to do the opposite........

Making the Manta stand higher will effect the way the car handles, maby for the better, but in my opinion for the worst

[GoinManta]

I will check on my Manta I have a fairly tall tire on one rim.. It was a odd tire I found to put on a spare rim.

I believe it was a 195/75r13 Odd tire size but it will give the height you can go too..

[RallyBob]

Originally Posted by Loeblich But does anyone knows for sure what's the "tallest" tire and rim I can use? Thanks a lot Javier Alvarez Löblich.

It depends on not only the height, but the width and wheel offset. The rear wheelwells are pretty tolerant, but up front you will generally have trouble with tire clearance at the lower valance (bottom lip - sheetmetal apron).

We used to run 195/70-13 and 205/70-13 tires a lot in the 1980's (back when those sizes were available from BF Goodrich and Vredestein), but we also ran high pressure gas shocks (Bilstein or KYB) to help 'lift' the car a bit higher. Any taller than that and there was always tire rub. This was usually on standard '8-hole' Opel steel wheels (5.5" wide). Running aftermarket wheels with greater positive offset changes the front suspension's scrub radius, and increases tire rub issues.

HTH,
Bob