[terry]

hi all. if i was wanting to go a larger tyre size. eg. 30inch is it possible with the standard gearing and with a 1litre motor.? currently iam running 205/70r 15. no i dont understand that configeration. i only understand tyre size in inches.what is 205/70r 15 in inches anyway? thanks for your help.

[mrw82]

for quite a while I have been running 30" muddies with standard 1 litre gearing and it was pretty good. the only problems I had was on steep hill climbs, It didn't have the power to get up them and If I stopped on one I had to kill the clutch to have any sort of chance of moving forward again.

on road wasn't a problem for me and when I brought crawler gears I got 4.16 ratio. which has the same high range gearing as the 1 litre but a lower low range. Im yet to test out the crawler gears (going out tomorrow to give them a work out) but from mucking around in the back yard I can tell the difference already.


when I brought my car it had 31"s on it. DO NOT GO THAT BIG. I reduced to 30" and it made a huge difference (so going up in size would have the same amount of negative affect, but it is still drivable) I am running them on ROH 15x7 sunnies with 2" spring lift and dont have any limiting problems with rubbing, it touches here and there but only just, not enough to worry about. I haven't had any problems with diff clearance.

I would suggest go ahead and fit a set of 30"s and save up for a set of gears. (not to mention wait for the aussie dollar to recover!!!)

if your in brisbane I am happy for you to come and have a drive and compare the difference. i live northside.

cheers, Mark.

[hugz]

mrw82 wrote:

when I brought my car it had 31"s on it. DO NOT GO THAT BIG..

Why? Only on 1L or do u recommend 30" max for all sierras?

[royce]

I had 31's plus body and suspension lift on my 1 litre with stock high range gearing and it pushed it better than my WT did

1 litre was in top nick and regularaly seviced and tuned, only mod was the fan was removed and a thermo fitted

[DieselZook]

terry wrote:

what is 205/70r 15 in inches anyway?

205 is the nominal section width in mm
70 is the profile of the tyre in %
R means it is a radial tyre
15 is the size of the rim in inches

so

The amount of rubber between the rim and road would be 205 x 70% = 143.5 mm
convert mm to inches 143.5 / 25.4 = 5.65 (approx)
now multiply this by 2 (because there is rubber above the rim as well as below it) and add the diameter of the rim
5.65 x 2 = 11.30
11.30 + 15 = 26.3 inches

so after all that a 205/70R15 is nominally 26.3inches high