TA22 mag wheels

**ta22fan** · 08-09-2009, 09:31 PM

Has anyone (in NSW) found a way to get 7-inch wheels RTA approved for a TA22 with standard front and rear suspension?

I've done a fair bit of research on this site and elsewhere, and it looks to be a problem. RTA standards in relation to alternative wheels (http://www.rta.nsw.gov.au/registrati...vsi09_rev4.pdf) cover two key points:

#1 - Wheel track must not be increased by more than 25mm beyond the maximum specified by the vehicle manufacturer;

#2 - Maximum allowable rim width increase above the widest optional wheel available for the axle assembly used (801-1200kg - which matches the TA22) is 39mm (1.5 inches).

In relation to point #1 - this basically comes down to change in wheel offset as I understand it - +25mm change in wheel track means +12.5mm change in offset on each wheel. I'm pretty certain that the factory wheel offset for my '74 TA22 is +35mm (I've got the original rims). To comply with the RTA regs, that would mean rims with an offset of no less than 35 - 12.5 = +22.5mm (say +23mm to be on the safe side). The largest +ve offset 7-inch rim that you can fit on to a TA22 (without spacers) is around +10mm without having the inside of the wheel/tyre coming into contact with parts of the front suspension. But a +10mm offset wheel is going to be 13mm more (wider) than allowed under the RTA regs - correct?

In relation to point #2 - the factory rims on the TA22 (LT and I think ST) were 13x4.5J - ie, 4-1/2 inch. Going with the RTA limit of 1.5 inches wider - that's a 6-inch wheel. I've found some info that indicates that the TA22 GT came with 5-inch rims standard (but still +35 offset) - so you could possibly win the argument to go to 6.5 inches. However at 6.5", you'll need to go to a lower +ve offset than +23 to keep clear of the front suspension. The RA28 (still a Gen-1 Celica) had a 5-1/2 inch wheel - don't know the offset of these tho. Problem here is that the rear axle in the RA28 is (I believe) not the same as the TA22 axle, so whatever may be Ok on the RA28 does not translate across to the TA22.

Based on this - looks like the widest wheel option that'll pass an engineering check will be 6-inch with a +23 offset? Major bummer if so - I've got a set of really nice 14x7" / 2P Cheviot hotwires that fit just perfectly, and look terrific.

**SilverRA23** · 09-09-2009, 10:03 AM

I know its very nice to have a car that is 100% legit, but what are the chances of a copper picking you up on having 7 inch rims not 6 inch? Not likely I would have thought.

I guess the other issue is insurance. Some insurers will specify a maximum width - which will often be different to the RTA.

**"Z" UTE** · 11-09-2009, 07:18 PM

ta22fan, the TA22/RA23/RA28 live axle assemblies are the same width. The RA28 just has a wider rear body.

TA23/RA23 and RA28 used a "T" series diff., as did the later model TA22's. The very early (1971-1972) TA22's had a smaller "D" series centre.

cheers Chuck.

**ta22fan** · 13-09-2009, 07:34 PM

Thanks Chuck. Even tho the difff's the same, I believe the axle shafts and bearings are different between the TA22, TA23 and RA23/RA28 - which makes it a different axle. The good news is that it sounds like an RA28 axle should drop into an TA22 without any modifications, and the this axle is spec'ed to take a 5.5" rim. Under the RTA reg's - I'd then be officially Ok to fit a 7" mag. The remaining problem is that a 7" rim with a +23 offset won't fit the standard front suspension, and a +ve offset any less than than won't meet the requirements either.

Have to say the RTA limits seem overly restrictive - +25mm in wheel tread width is hardly anything.

I'm assuming that folks running 7" mags on TA22's (seem to be pretty common) are doing it on the Q.T. - so guess I'll do the same.

Paul.

ps - good to know the axle width info for the RA28 - I'm working on putting together a set of technical info on Gen-1 Celica's - will add this to the file. Will publish it when I have it done. Don't suppose you have the track width for RA23/RA28? That would give me the rim offsets (hard to find offset info anywhere for these models).

**LT1986** · 13-09-2009, 08:12 PM

....hmmm, will an engineer okay the increase and mod plate it accordingly? Were talking about modifications that ar very straight forward

**ta22fan** · 13-09-2009, 08:31 PM

LT - I guess that's what I'm asking - if it'll pass an engineer inspection with 7" rims - it's all good. Just wanting to know if anyone has managed this. RTA regs suggest no-can-do.

Paul.

**"Z" UTE** · 13-09-2009, 10:14 PM

Paul, direct from the Toyota 1977 Celica owners manual:

Front track ,TA23, RA23 and RA28 1335mm, but with 5J x13 rims we have 1350mm

Rear track, TA23, RA23 and RA28 1295mm " " " " " 1310mm

cheers Chuck.

**ta22fan** · 14-09-2009, 04:51 PM

Thanks heaps Chuck.

If my arithmetic is right that leaves me with:
- TA22: 1355mm rear axle, 1285mm rear track implies +35 offset 13x4.5" rims
- TA23/RA23/RA28: 1355mm rear axle, 1295mm rear track implies +30 offset 13x4.5" rims
- TA23/RA23/RA28: 1355mm rear axle, 1310mm rear track implies +22.5 offset 13x5" rims

I've seen a copy of the RA23/RA28 owners manual that lists 14x5.5" rims as options on the RA23/28 ST (2000), and on the RA28 GT.

So I think a 14x7" mag wheel with a +10mm offset gets a pass from the RTA on the RA23/RA28, and hopefully also on the TA23 (meets both the maximum rim size and track width criteria).

I think I could make a pretty solid case for the TA22 on the basis that the TA23 is mechanically essentially the same as the TA22 (drive-train, suspension and brakes all the same I believe), meaning that if a 14x7 rim is Ok on a TA23, it's also Ok on a TA22. Small gap in this because the rear axle in the TA23 is slightly different to the TA22.

I guess find a friendly engineer and see what he's got to say....

Paul