27 inch tyres

scarhead

scarhead

Forum Member
Joined
Jun 23, 2014
Messages
23
Location
Lalor, Victoria, Australia
Car Year
1987
Car Model
Brumby
Transmission
4 speed maunal
i'm getting a 2 inch lift, after that will 27inch tyres on 14inch rims fit the Brumby ok? they don't foul on the inner guards do they?
 
Gidday SH

You need to ask someone like Bennie about this.

Apart from binding on the guard liners and wheel arches, some other things to watch for are binding or fouling on the steering components, brakes, brake lines, suspension arms, spring perches and the like.

Are you changing the rim size from standard? This may also have an impact.

If the rolling circumference of the rim/tyre is changing, you may need to have your speedo re-calibrated.

Have you factored in the change in overall gearing that this change will have?
As the gearing gets higher, it has an impact on acceleration because it has the effect of reducing the apparent torque available for this purpose.
The car will be doing less rpm at any given speed, but will get there in a more leisurely fashion.
You will also have less torque available at low revs - i.e. in off-road situations.

Just a few thoughts, mate.
 
Last edited:
Cheers, I actually didn't know any of that. I currently have 13 inch wheels on it, wanted to go bigger for more clearance off-road. The tyre width is nearly the same as what's on it.. Currently 75, new ones are 76.
 
G'day again SH

When you say the width is the same, do you mean the profile ratio? Or the physical (measured) width?

You can check the effects on the car gearing and speedo at any one of many tyre size calculator sites. This is the one I have bookmarked:

https://www.inawise.com/tyre-calculator/tyre-size-calculator.html

The change in gearing will be (roughly) proportional to the change in speedo accuracy.

If you feed 175/75 x 13" and 175/75 x 14" into the above calculator, you will find that it reduces the actual speedo reading at 100 Kmh by about 4% - i.e. the speedo will be reading 96 Kmh when you are actually doing 100 Kmh (it is actually 4.29%).

In this example, the reduction in apparent torque in any gear or at any speed will be (roughly) equal to the square of the increase in rolling circumference, which is about 1.0429. The square of this number gives you 1.0429 x 1.0429 = 1.0876. Therefore the effective decrease in torque will be approximately 8.76%. This will be quite noticeable, IMO.
 
My mistake, I just checked. The tyres I have now are 175/70r13. The new tyres I'm looking at are 216/76r14.(14 inch rims obviously)
 
So ultimately, I'd be better off sticking with the same tyre size to save a large $ outlay and headache?
I'm trying to decide between 2 options I've found..
14 inch rims with A/T tyres (216/76r14)
Or
Just 175/70r13 A/T tyres..
 
^ I think that the tyres you are looking at will be 215/75 14", not 216/76 14".

I very much doubt that the latter tyre size has ever been made by anyone! But I am quite happy to be corrected if wrong about this.

215/75 14" will give you a speedo error of approx. 18% and an effective change in torque of 1.1789 x 1.1789 = 1.3898, or about a 39% decrease in torque. This will be very, very noticeable! To the point where it could make the car horrible to drive.

A 175/70 14" would be far more appropriate, giving you a lift of around 1/2" (i.e. a 1" increase in overall diameter). Your speedo will also be accurate to around -4%, so acceptable if you are careful.

If you fit some 1" HDPE strut top lift blocks, this will give you an extra 1.5" clearance, without causing any significant problems.

You might be able to fit 205/60 14" (if you can find this size - 195/60 14" might be easier to source ... ), which will be almost the same as 175/70 14" in diameter and rolling circumference.

You need to hit some tyre dealers or web sites to find out what sizes are readily available, and what they cost!
 
To answer the original question:

The larger tyres will most likely need some guard trimming up front, how much I don't know as I've not done it before.

Ausubaru might have the answer for you. Unfortunately there doesn't seem to be much work going on to ask of people but there may still be members around that know what's needed.

What you can do is look at a set of road tyres then fit you larger rims and tyres for offroading - that way you minimise your on-road time with the larger tyres, thus reducing wear on expensive rubber.

Many have just kept the stock drivetrain and find it to be ok, not ideal unless you want to go into a full blown gearbox build for offroading...

Cheers

Bennie
 
^ Thanks for chiming in, Bennie.

You having just a tad more experience with the L Series than I have ... :poke: ... just a bit ... :rotfl:.

SH, that tyre size you are looking at is nearly the same size as my 1968 LC rims/tyres. While the LC had larger rims, it had narrower tyres - 7.50" wide on 16" rims (7.50R16).

It had a 3.8L (very) long stroke, six cylinder donk to turn them around with ... :iconwink:.

Even though the rims you are proposing to fit are smaller, the LC wheels are about 29" rolling diameter. There is one that parks around the corner from us here, and I just nicked out and measured the wheel ...

A tyre this size will dramatically increase your un-sprung weight, and the overall performance of your car.

The almost 2" increase in width will give your insurer the heebie-jeebies, and almost certainly void your insurance.
Mine is very toey about increasing from 215/60 16 to 225/60 16! Or fitting other than OEM rims, for that matter - and we are both over 65 y.o. with no accident history in which we were in any way at fault for over 40 years!

Methinks that there are much better ways to improve your lift and the off-road performance of your car, without voiding your insurance. It appears to me that what you are proposing will cost you a lot of money, and be very disappointing for you.
 
Last edited:
BTW, I just had a look at that fleabay advert.

I wouldn't touch those tyres with a 40 foot barge pole, even if it had a prophylactic on both ends ... :puke:

"mixed casings"; "some puncture repairs before re-treading"; etc; etc. UGLY.

Even when young and poor when we used re-treaded tyres on several cars, I insisted that the re-treader (Beaurepaire) collect a set of good, matched (Michelin) casings. Then had those re-treaded for me. Then let them sit for 4 weeks to cure properly. It takes that long for the molecular bonds to get rid of the heat absorbed during the re-treading process.

The tread pattern on a tyre has very little effect on its on-road handling, except when the road is wet. Almost all of the handling characteristics of a tyre come from the casing. Guess what having four different casings will do to the handling of any car ... :puke: :puke:
 
Hey Scarhead. To fit 27'' tyres on 14''s, youll need a 2" body lift for them to clear. Fresh springs would help too. You may need to trim the front bottom edge of the front guard to have them clear.
 
scarhead said:
these are the 13" tyres i was originally looking at before thinking about going 14"

https://www.ebay.com.au/itm/191157337298?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Click to expand...

I agree with RB, do not get those tyres! Apart from retreads being illegal in Victoria (I think also nation wide but as least Vic), handling is poor & reliability is worse. Imagine what would happen if the tread delaminates at speed. this happened to a mate of mine on a factory tyre & is far more likely on a retread :eek::shake:

I wouldnt go 175 if you're getting new tyres, 205 width tyres will be much better if they fit
 
Gidday NL
I wouldnt go 175 if you're getting new tyres, 205 width tyres will be much better if they fit
Click to expand...

I don't think that the Brumby has sufficient weight to hold that width tyre on the road in the wet. I would really recommend 185, at the maximum. The Brumby is a very light car by comparison with any Forester, or even the 4WD L series Sportswagon.
 
I had 205s on a little FWD Corolla. Modern tyres are very different & the more rubber you have on the road the more grip :lildevil:

Factory tyres would be larger but are restrained by cost & economy figures. More rubber = more weight & more friction so less economy. But remember its this friction that is the grip we all want :iconwink:
 
Hi Scarhead (I bet there's a story behind that one ;) )
I'm currently running 185/65/14 on my L, road pattern stuff, but I haven't had an off road situation (at least in the dry) where they've been the sole cause of getting stuck.
My plans for the tyres/lift are to get a 2 or 3 inch body lift and get a spare set of 14s with 27" muddies, probably kumhos. Or use my 14s for them and get a set of stock 13s for the road. I'll wait and see how I go for wet road traction after my EJ swap, as my desert rat 14x7s (14x6? Can't remember) can fit wider tyres.
Not going to happen for a while but that's the plan at least!!
 
Also, I was looking at those eBay tyres too. I do a lot of mid-speed gravel road stuff with my volunteering with RallyWA so they'd be a good idea. My concerns were related to highway speeds with them being retreads. Thought about carrying them in the boot until the tarmac ended then stopping to swap them but it's too much hassle. Doable, but lots of time lost. Just a thought.
 
i'm steering away from the retreads now as the car will sit in the shed most of the year and apparently retreads don't like to sit...

and yes tom, there is a story to my username.. check the thread ;)
 
You must log in or register to reply here.
Back
Top