Dropping from a 40 profile to 35 profile, how much height can i lose?

[Razor04]

I'm currently running 235 40 17 tyres on 9" rims on the rear and am getting a slight contact with the arch lip on the driverside only (because of my weight sitting on that side), this only happens if i hit an exceptionally bad pothole etc or a sudden dip in the road surface at speed on the mortorway (due to the car sinking down lower at high speed)

my question is: if i drop to a 35 profile tyre how much in tyre height will i be able to lose? will it prevent contact with the arch lip or is the difference in height not really worth it?

the other option is rolling the arch lips but this is a last resort really because i have mint rear arches and i dont want to crease paint, create a trough for water to sit in, corrosion etc.

any views?

[Marf]

Roll your arches

If you have perfect arches with zero corrosion or cracked paint you are very unlikely to end up damaging the paint. You can lay sealant in the trough to stop it gathering water.

[Rogue]

my question is: if i drop to a 35 profile tyre how much in tyre height will i be able to lose? will it prevent contact with the arch lip or is the difference in height not really worth it?

You'll have 11.75mm more clearance.

[SimonPearse]

11.75 mm......

the tyre width is 235mm
a '40' profile tyre has a height of 40% of the width =255*0.4=94mm
a '35' profile tyre has a height of 35% of the width =255*0.35=82.25mm
difference is 94-82.25=11.75mm

expect the handling to be severely compromised

[Kongaroo]

I don't think you'll find any 235/35/17 tyres for sale - it's a size that nobody seems to make?

[Harry]

The shoulder design of the tyre itself is important. The way it falls away. Short part. Falken GRB 452 will offer the greatest clearance over other brands. Is a start. 245 35 17" will still be lower that your current. Plus be a better size on 9". We used GRB 245 on both 8.5" 17" plus 9" 18".

Off set is another key. We were 37 mm off set and 38 mm top of the head. Set very low on Teins. Will work out the 245 35 to 235 40 difference later. The *Profile* matters a lot for that extra clearance 40 > 35. GRB 452. (35 off set?).

[Harry]

603 mm < 620 mm (- 17 mm) Gained (less-lower-smaller-more clearance, etc.) by going (245 35 17") over 235 40 17". Its 24" wheel about the same as stock 15" factory wheels. Front is 23" BTW.

Uprated TRD: bush, roll bars, coil overs 4 & 8 kg spring values, laser alignment to stock MR 2 settings, upper strut bars, 32 & 33 psi tyre pressures, etc. Will control the centre of roll and again help contact plus clearance with - the obvious improved handling. Bouncy soft springs and fatigued shocks will help contact be made.

[Harry]

We used: 215 40 16" Falken GRB 452 with 7.5" wide Advan RG Gold rims 37 mm off set ( = 23" stock height wheel size) 245 35 17" Falken GRB 452 with 8.5" wide Advan RG Gold rims 37 mm off set ( = 24" stock height wheel size)Set that low that a flat bed truck just made it on - just! No clearance contact arch or other contact issues - through high g force cornering tests/ed.