Are your 33"s actually 33" in diameter?

[BUSHWHACKER]

I had a couple of trucks here recently, both shod with 33" mud tyres. The trucks were parked front bumper to front bumper, both have 2" bodylifts but I fitted 2" balljoint spacers to one of them. The 33"s on the B/J lifted truck didn't 'look' like 33"s anymore , now due to the extra height compared to the other truck on 33" BFG muds, so I had a measure.

All tyres were @ 32psi and were stone cold during the measuring.
Spirit level across the top of the tyre, levelled and then measured from the bottom of it to the floor.

33/12.5/15 BFGoodrich M/Ts (New pattern) actually measured 32" (Newish)
33/12.5/15 Kumho Road Venture M/Ts actually measured 31" (Newish)
33/12.5/15 Marshal Venture M/Ts actually measured 31" (Worn but loads of tread)

Would be interesting to find out if other brands of 33" tyres are actually 33".

[BUSHWHACKER]

I had a couple of trucks here recently, both shod with 33" mud tyres. The trucks were parked front bumper to front bumper, both have 2" bodylifts but I fitted 2" balljoint spacers to one of them. The 33"s on the B/J lifted truck didn't 'look' like 33"s anymore , now due to the extra height compared to the other truck on 33" BFG muds, so I had a measure.

All tyres were @ 32psi and were stone cold during the measuring.
Spirit level across the top of the tyre, levelled and then measured from the bottom of it to the floor.

33/12.5/15 BFGoodrich M/Ts (New pattern) actually measured 32" (Newish)
33/12.5/15 Kumho Road Venture M/Ts actually measured 31" (Newish)
33/12.5/15 Marshal Venture M/Ts actually measured 31" (Worn but loads of tread)

Would be interesting to find out if other brands of 33" tyres are actually 33".

Wouldn't it?

[Wolfracer]

Wouldn't it?

For you Vince I will measure tomorrow...

maybe

[muddle]

Ill measure my 31s and see if same applies to them.

[Balllsy]

I'll measure mine tomorrow too when I go to mates house

[stormforce]

i got 285x75x16x which should be close to 33's so i'll measure them up later

[bonynoliver]

My, almost new, GTRadial Adventuro M/T 33 x 12.00 R15 tyres measure a nats tat under 32" in diameter.

Still a far better fit than the over-oversized 35's that came with the truck which rubbed the rear bodywork off-road (despite a total of 6" of lift!)

[Wolfracer]

i got 285x75x16x which should be close to 33's so i'll measure them up later

32.83 inches by my reckoning. Will be interesting to see the actual.
Must go and measure mine once i've cracked the frost of the tape measure...

[Kwakka666]

As you're measuring the wheels whilst fitted, shouldn't the wheel they're mounted on be considered as well?

Tyres are 33" 12.5's but if wheel is 10" or maybe 8" would it not affect the diameter slightly.

or am I chatting rubbish?

[stormforce]

You are correct as it will also depend on the width of the wheel the tyres are fitted to

[Wolfracer]

As you're measuring the wheels whilst fitted, shouldn't the wheel they're mounted on be considered as well?

Tyres are 33" 12.5's but if wheel is 10" or maybe 8" would it not affect the diameter slightly.

or am I chatting rubbish?

Slightly affected due to the curve of the side wall, but if we are being that scientific, then they should all be at the same pressure and temperature as well.

And, no, I've not measured mine yet....

[j.hell]

are you taking the weight of the truck in to consideration?

[BUSHWHACKER]

are you taking the weight of the truck in to consideration?

Yes and altitude air pressure/temperature.

[Kwakka666]

Slightly affected due to the curve of the side wall, but if we are being that scientific, then they should all be at the same pressure and temperature as well.

And, no, I've not measured mine yet....

Was just a thought as the 32" BFG's in Vinces first post are on 8" wheels
(I think) not to be super scientific, that way madness lyes.

[andy_enuff]

Well they should be the SAME but with the weight of the truck on them they might be 32" total like you found with the first set due to the lower part of the tyre being compressed. Doesn't account for the inconsistency though...

Did you measure the lower wheel rim to the floor and the upper wheel rim to the spirit level? that would maybe give you some interesting results in terms of the lower compression (maybe the material means they compress more?) and the uncompressed upper width? (in addition to your total above)