Steering feels light

H

hmatt

Hi just looking for a bit of advice. Just fitted some 17" AEZ XYLO alloys and they look great but the steering is a lot lighter and the cars developed understeer. I've got decent tyres on it - Toyo's - so not quite sure what's happening. Before i had the standard 15" alloys with low profile (195x15x50) Goodyear F1's and it handled beautifully. Do i need to drop it to get the handling back or is it due to something else.

Any advice appreciated, Matt
 
The OE 15" alloys will handle better than 17s, unless you go for some expensive lightweight ones. AEZ`s, as far as i can see are a bit `lardy` compared to other brands. Bigger isn`t always best!

I knocked about 2kg of each wheel when i fitted my 16" Rota`s, the difference it made to handling and speed was staggering.
 
Could be that the tyres are still new and the rubber hasn't got 'that grip' yet that you get with tyres that are worn down slightly??

Won't having bigger wheels also make the speedo inaccurate?? something i've read somewhere
 
Yes a larger wheels and tyres will make your speedo out but it depends on the wheels size and tyre profile. there are many convertion charts knockin about the web.

I can only think of the previously suggested tyre pressure being to high to make it feel light coz really it should feel heavier. With a heavier wheel and i assumer a wider tyre as the standard 15's are 195 whereas most 17" packages come with 205 or 215 tyres
 
i'll try dropping the pressure - they're at 31psi at the mo so i'll maybe put them down to 26 (what are you folk running your tyres at?).

Circumference-wise the new wheels are pretty much the same as the originals. The lower profiles i had on the originals meant the wheels were smaller and hence the speedo was reading about 5% above the actual speed whereas now it's more or less where it should be. Acceleration is a bit slower mind and i'm wondering if the drop in handling is due to the fact the car's now a wee bit higher due to the bigger (ie back to the original size) wheels.
 
26 would be too low, tyre pressure will be the same as the factory alloys i believe. This should be on a sticker in the door shut.
 
Different size wheels and profile tyres will feel different, I just upped from 185/65/15 to 205/40/17 and there is a big difference even with lightweight wheels (no change in unsprung weight at all in my case).

In my case the steering feels lighter and follows the bumps and dips in the road more, there is a little understeer and a rougher ride and I feel I have to turn the steering wheel further to get the same line. On the other hand there is not as much roll when cornering quickly and much less 'wandering' on the motorway with heavy, gusty crosswinds.

As well as the size and profile difference the tyres are slicker than my old ones and have only done a few hundred miles so I expect are also still 'running-in'.

The roads seem quite greasy right now too.

I'm probably running a few PSI too much all round, I'm running them about 2 PSI above the originals.

Am I right in thinking that in winter the colder, denser air put into cold tyres will mean more pressure when they get up to normal driving temperature? If so would this affect a lower profile tyre more or less? Would it make enough of a difference to notice?

I really want to get out onto a dry track and throw it about a bit to see if I have any less grip now or if it just feels like it - it'd be handy to know before I have to find out.

This site tells you more than you would ever want to know about wheels and tyres - I can't vouch for it's accuracy myself but most of it looks about right.
 
the two diff pressures stated are for usuall driving with up to half load and then for maintained higher speed with a full load ie long motorway trip with 4 or 5 people and luggage.
 
Rick said:
Standard pressures are 30psi front and 33psi back IIRC
Click to expand...
just curious as to why theres more pressure in the back to the front.
surely its more in the front because of the extra weight of the engine,
im running 33 front and 31 back
 
ha, went to the garage to find the tyres were at 38 all round! Put them down to 32 front and 30 at the rear and got a much improved driving response - steering felt how it had with the other alloys and the ride was a bit less bouncy too. A couple of hundred more miles on the tyres has helped scrub them in a bit too i think and overall the car felt a lot more positive and grippy.

Also, having read Maxpower the other day, filled the tank with Shell vpower petrol and was pleasantly suprised to get an extra 20 miles out of half a tank. Also, unless i'm kidding myself on, the engine felt stronger and more responsive too. For an extra few quid a throw i think i'll put in the pricier juice from now on!
 
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