Tyre Profile GS

[maseratimike7]

Is anyone running a larger tyre profile to OEM on the gransport?



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[spkennyuk]

Is anyone running a larger tyre profile to OEM on the gransport?



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Surely that would throw the speedometer accuracy out as the rolling diameter of the wheel would increase unless you changed the alloys to 18 inch to compensate.

 

[BL330]

Yes I'm running 18 inch wheels instead of the 19's, so have 235/40 zr 18 on the front and 275/35 zr 18 on the rear.
I run 15mm spacers and they fill the guards very nicely.
The higher profile tyres are so much more comfortable than the 19's, and I have mostly smooth roads around here anyway.
A lot of owners out here increase the width on the rear 19" tyres from 265 to 275 to increase the 30 profile height.

 

[Zep]

I have seen people going for the 275 tyre too. There is very little in it in terms of speedo reading. I would check the speedo against a GPS speedo on your phone and then do some comparisons between tyre sizes on one of the calculators. Allowing for wear on your existing tyres obvs.

 

[mjheathcote]

I've 275/245 18's on mine so slightly wider.
I do have wider FD/Forgestar F14 rims however too.

 

[Twinspark]

In the American forum there were some people running +10mm wider all round. Doesn’t affect the speedo too much and the tyre doesn’t look as “stretched” on the rim.

That said I remember someone saying the spokes stick out beyond the tyres so there’s no additional protection had.

When I bought my car it had the wider setup, albeit with 255 up front which I don’t recommend as it rubs. 275 and 245 are easier to find than the original 265 and 235 because the former is shared with the Corvette and some other models.

 

[maseratimike7]

Thanks for the feedback.

Reason I was asking is I have to change both rear tyres again and have only covered 1800 miles between changes.

Where I live there are lots of speed bumps which I crawl over but I am still getting scoring and bubbles on the sidewall of my tyres.

I was hoping that by increasing the profile it might prevent this from happening!

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[CatmanV2]

+10mm wider all round.

Wider isn't profile. So perfectly possible to get a wider tyre, with a lower profile and not affect the speedo at all. I suppose technically the OP could have a higher profile with a narrower tyre and get the same effect. I guess that's not what he was after though

FWIW mine is specced for 275/35 but apparently 275/40 work just fine and there is a far greater choice

C

 

[jasst]

I am running 245 on the front, and when the rears get changed this winter will be goingfor275, so 10mm wider all around.

 

[maseratimike7]

Think I will try the wider size see if this makes a difference to the lifespan I get out of them

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[BL330]

"scoring and bubbles on the sidewall of my tyres." ??
I had a bubble once from a pothole hit, but scoring suggests rubbing on the guard. Might need to look at your suspension set up.
When I bought my car it handled like a pig, tramlined terribly and scrubbed out the rear tyres. When I had it aligned they found the rear tracking was out 15 degrees! Previous owner's service team had no frigging idea.

 

[Zep]

Wider isn't profile.

Well it kind of is, a 275/35 has 4mm more sidewall than a 265/35, as it is a percentage of the width. Whether that makes a difference is anyone’s guess.

 

[CatmanV2]

Well it kind of is, a 275/35 has 4mm more sidewall than a 265/35, as it is a percentage of the width. Whether that makes a difference is anyone’s guess.

Yes, true

C

 

[jasst]

This is useful, as you can see, the difference between a 265/30/19 and a 275/30/19 is 0.8 % https://tiresize.com/comparison/

 

[maseratimike7]

"scoring and bubbles on the sidewall of my tyres." ??
I had a bubble once from a pothole hit, but scoring suggests rubbing on the guard. Might need to look at your suspension set up.
When I bought my car it handled like a pig, tramlined terribly and scrubbed out the rear tyres. When I had it aligned they found the rear tracking was out 15 degrees! Previous owner's service team had no frigging idea.

Tracking is fine just had a hunter alignment when tyres were still good. I suspect it's the speed bumps causing problems as can't see anything else that could cause this.

PSI are good, tracking is good so I'll try the larger sizes and fingers crossed.

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[GTVGEOFF]

If anyone has the wider tyres fitted have you noticed any improvement in ride quality with the higher side walls? On the 19inch wheels.

 

[boomerang]

275 on 19 here as well.
Better rim protection, a bit more comfort, better filling of the arches and speedo exaggeration softened.