Uniroyal Tyre pressures

F

Frankie169

Member
 North Somerset
My new to me 2.0 is currently on Uniroyal Rainsport 225/45/17 tyres

Can anymore tell me the recommended tyre pressure for these, dealer seems to have put pressures of 38f/42r in them, assume he took this from the manual but these aren’t run flats so thinking this might be the cause for an overly harsh right.
 
There will be a label inside your door jamb
Frankie169 said:
Thanks, probably explains the harsh ride if mine are at run flat pressures
Click to expand...

There will be a label inside your door jamb showing the required pressures for your car. These suggested pressures are not dependant on tyre construction, so are the same whether your using runflats or not since the primary purpose of the air in tyres is to support the load of the car.
 
Fady said:
There will be a label inside your door jamb


There will be a label inside your door jamb showing the required pressures for your car. These suggested pressures are not dependant on tyre construction, so are the same whether your using runflats or not since the primary purpose of the air in tyres is to support the load of the car.
Click to expand...
Because the side walls on normal tyres are so thin compared to run flats, they create more bounce when inflated to the door pillar pressure, which effects the ride and handling, dropping the pressure by around 6 psi make the ride more compliant.
 
Chippie said:
Because the side walls on normal tyres are so thin compared to run flats, they create more bounce when inflated to the door pillar pressure, which effects the ride and handling, dropping the pressure by around 6 psi make the ride more compliant.
Click to expand...
Yup, here we go with this old chestnut again. Anyone still inflating non-runflat tyres to full run-flat pressures must have industrial strength fillings in their teeth, no inbuilt ability to sense the handling characteristics of their car, no mechanical sympathy, a willingness to blindly do what the book says without even attempting to try anything different, or a combination of all those.
A two minute read through this forum (or indeed, any other BMW car forum) will provide clear evidence that reducing the pressures when fitting non-runflat tyres makes a huge difference to comfort and handling.
Exact pressures are defined by several factors, but common consensus seems to be F30-34, R32-36.
Both my E85 and my E89 use the same size 18" staggered set up and the same size tyres, yet I run the E85 at 32F, 34R and the E89 at 34F, 36R. Both sets of figures give the optimum handling to suit me.
 
Experiment and go with what you like or feels right.
After 5k miles check tyres for wear.
From memory i think the 23i recommends higher pressures than any other variant.
Time has past, tyre tech. changes...you are a test pilot..try different settings.
 
You must log in or register to reply here.
Back
Top Bottom