Wheel rim and offset advice please

[SeanF]

Hello all,

 

I know this has come up many times but I could not find the exact answers to my questions despite exhaustive searches so I would appreciate some straight advice please.

 

My car will not be "uprated" in any way. Original stub axels, hubs, drive shafts, lever arms etc but I am rebuilding on a brand new CTM chassis and have replaced UJ's etc.

 

I am looking to buy some Minilite type alloy wheels but am stuck in a muddle of rim size, offset and tyre size. I understand that the original steel wheels are 5.5j rims and have an offset of +6mm. Is this correct?

 

I have been talking to a supplier of alloy wheels who offers a 6j wheel with an 8mm offset but their "identical" 5.5j wheel comes with a 15mm offset. They tell me that both fit the TR6 with no need for spacers and it is this that I am trying to verify. Does anyone have experience of whether a 5.5 rim with 15mm offset will fit a 6 comfortably without spacers? (I think they are MG wheels )

 

Secondly, will it make any meaningful difference on an original suspension / steering set up whether I fit 5.5 inch rims or 6 inch? I believe that the wider wheel will put greater strain on the susp set up and give a heavier steering but is this noticeable or significant and is it more beneficial to have the correct 5.5in rim or the lower offset........or does it matter?

 

Thirdly, I have been advised that 195/65 15 is tyre size to go for with 5.5 rims but that these will also fit 6in rims. Again is this best advice?

 

Many thanks in advance for advice on any/all of the above.

 

Sean

 

[peter clarke]

Minator Minilite wheels 15 x 51/2 are an excellent wheel with 195 tyres. You just need to check the clearance between the inside edge of the rim and the top suspension arms and bolts/nuts at the top ball joint. If the outside bolts protrude thru the nuts too far they can foul the rim on full lock. There are no issues on the rear.

My car is a daily driver and the wheels are over 10 years old and look new with no gutter rash thanks to the tyre size and no cosmetic change to the surface.

[saffrontr]

Sean,

 

Standard 5.5J TR6 steel rims have a 3.5" backspace. I have had a number of sets of alloy rims over the years including 6J Cosmics which had a 4" backspace and 6J ARE also with a 4" backspace. Both of these types of alloy did touch the top suspension arms and also rubbed on the rear shockers and I used quarter inch spaces and longer studs to solve the issue. On both types of alloy I used 195 x 65 tyres which didn't cause a problem with rubbing when used with the spacers and I now use the same tyres on standard steel rims without spacers with no rubbing.

 

Backspace on TR6 rims is the issue and anything greater than the standard 3.5" could cause some minor fouling or rubbing at least in my experience.

 

cheers

 

Derek

[SeanF]

Thank you Derek and Peter for your replies.

[Steves_TR6]

Hi Sean

 

Offset is quite a subject!

 

I recently wanted to purchase a second set of wheels for my Alpina / BMW and the whole subject of offset confused me at first....

 

Offset is how far Inboard to the car the wheel sits from the default of the mating face being in the middle of the wheel.

 

Offsets are quoted most often in mm, whereas wheel widths are in inches!

 

So if you have a 6” rim witha 20mm offset it will be sitting 20mm further into the car than is the wheel had zero offset.

Thus the bigger the offset the greater chance of fouling.

 

Minator wheels for the tr6 fit well, aside from sometimes fouling steering/suspension components/bolts as mentioned already.

Ive had them on 2 cars now.

I’ve not seen offsets quoted for original TR wheels or for the Minators, would be very helpful if they were.

 

Hth

 

Steve

[Tom Boyd]

ET15 iirc for the genuine Minilites

[Nigel A]

I purchased genuine Minilites from Hamilton Classics (and received a discount as a Register member)

 

They fitted perfectly with no fouling.

 

Later I used new bolts when replacing the top ball joints and had to grind them down to prevent fouling - should have used the old bolts!

 

Cheers

 

Nigel

[SeanF]

 

I’ve not seen offsets quoted for original TR wheels or for the Minators, would be very helpful if they were.

 

Hth

 

Steve

 

Hi Steve,

This is where I saw the quoted offset of 6mm for the TR6 not sure if its correct or not.

http://www.mossmotoring.com/tire-wheel-plus-sizing/

Were your Minators 5.5j or 6J?

 

 

ET35 iirc for the genuine Minilites

 

Hi Tom, offset of 35 seems very big for a TR6? Wont they foul the suspension with that level of offset?

 

Does anyone have a view on the 5.5J v 6J question on a standard set up?

 

Cheers,

 

Sean

[JochemsTR]

I am driving 7J x 15....Offset 0.

With 8 mm spacers on rear and 3 mm spacers on front.

The rear is not critical, the front may cause an issue on the upper wishbone arms.

Tire / Rim combination:

165 fits on 4,0 - 5,5 rim

175 fits on 4,5 - 6,0

185 fits on 4,5 - 6,5

195 fits on 5,0 - 7,5

205 fits on 5,0 - 8,5

215 fits on 6,0 - 8,5

TR6 Steelrims have an 7mm offset.

Jochem

[TriumphV8]

As Jochem says, the 7x15 offset = 0 are the limit.

 

This means the wheel is 3,5" to the inside when its close to hit the wishbone.

On the outside my limit with 0 degree camber and 205/65 wheels is 3,5", too.

 

So you can play with the sizes to make a nice fit.

I would go for 6" with a little offset (wheel more in)

 

This is a modified 6" wire wheel centre laced with more

offset to get it unter the wheelarch. Its a lot of work!

 

[Steves_TR6]

Thanks Jochem and Andreas, good info.

 

So.... 7*15 0 offset but with spacers so effectively offset is -8mm rear and -3mm front.

 

This would imply 6*15 offset 0 will fit fine, or even modest offset should be ok since the wheels are 25.4 mm narrower, therefore 12.7 mm more offset ‘available’

 

Steve

[Tom Boyd]

 

Hi Steve,

This is where I saw the quoted offset of 6mm for the TR6 not sure if its correct or not.

http://www.mossmotoring.com/tire-wheel-plus-sizing/

Were your Minators 5.5j or 6J?

 

 

 

Hi Tom, offset of 35 seems very big for a TR6? Wont they foul the suspension with that level of offset?

 

Does anyone have a view on the 5.5J v 6J question on a standard set up?

 

Cheers,

 

Sean

 

Apologies, i meant to type ET15.......!

[saffrontr]

A standard 5.5" steel rim is 6" overall width over the lips hence with the standard 3.5" backspace this gives an ET of 0.5" or 12mm. Anything greater than this and you run the risk of having to use spacers certainly at the front.

 

cheers

 

Derek

[JochemsTR]

Thanks Jochem and Andreas, good info.

 

So.... 7*15 0 offset but with spacers so effectively offset is -8mm rear and -3mm front.

 

This would imply 6*15 offset 0 will fit fine, or even modest offset should be ok since the wheels are 25.4 mm narrower, therefore 12.7 mm more offset ‘available’

 

Steve

 

 

Yes, based on this you can calculate pretty much any version you like....

as mentioned, front is most critical....

 

Jochem